diff --git a/NAMESPACE b/NAMESPACE
index baf540162..c03ad46bb 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -110,6 +110,7 @@ export(palette_okabeito)
 export(palette_pizza)
 export(palette_see)
 export(palette_social)
+export(palette_tol_discrete)
 export(pizza_colors)
 export(plots)
 export(scale_color_bluebrown)
@@ -138,6 +139,7 @@ export(scale_color_see_d)
 export(scale_color_social)
 export(scale_color_social_c)
 export(scale_color_social_d)
+export(scale_color_tol_discrete)
 export(scale_colour_bluebrown)
 export(scale_colour_bluebrown_c)
 export(scale_colour_bluebrown_d)
@@ -164,6 +166,7 @@ export(scale_colour_see_d)
 export(scale_colour_social)
 export(scale_colour_social_c)
 export(scale_colour_social_d)
+export(scale_colour_tol_discrete)
 export(scale_fill_bluebrown)
 export(scale_fill_bluebrown_c)
 export(scale_fill_bluebrown_d)
@@ -190,6 +193,7 @@ export(scale_fill_see_d)
 export(scale_fill_social)
 export(scale_fill_social_c)
 export(scale_fill_social_d)
+export(scale_fill_tol_discrete)
 export(see_colors)
 export(social_colors)
 export(theme_abyss)
@@ -199,4 +203,5 @@ export(theme_lucid)
 export(theme_modern)
 export(theme_radar)
 export(theme_radar_dark)
+export(tol_colors)
 import(ggplot2)
diff --git a/R/scale_color_flat.R b/R/scale_color_flat.R
index b785d473d..b5c125a9e 100644
--- a/R/scale_color_flat.R
+++ b/R/scale_color_flat.R
@@ -153,6 +153,7 @@ scale_fill_flat_d <- function(
   )
 }
 
+
 #' @rdname scale_color_flat
 #' @export
 scale_fill_flat_c <- function(
@@ -271,10 +272,10 @@ flat_palettes <- list(
 #' which are the two scale useful for discrete or gradient color scales,
 #' respectively.
 #' @param reverse Boolean indicating whether the palette should be reversed.
-#' @param ... Additional arguments to pass to [`colorRampPalette()`][colorRampPalette].
+#' @param ... Additional arguments to pass to [`grDevices::colorRampPalette()`].
 #'
 #' @details This function is usually not called directly, but from within
-#'   [`scale_color_flat()`][scale_color_flat].
+#'   [`scale_color_flat()`].
 #'
 #' @export
 palette_flat <- function(palette = "contrast", reverse = FALSE, ...) {
diff --git a/R/scale_color_metro.R b/R/scale_color_metro.R
index bd27261c0..93a0f2f4f 100644
--- a/R/scale_color_metro.R
+++ b/R/scale_color_metro.R
@@ -232,7 +232,7 @@ metro_palettes <- list(
     "red"
   ),
   contrast = metro_colors("blue", "green", "amber", "purple", "red"),
-  light = material_colors(
+  light = metro_colors(
     "light blue",
     "red",
     "yellow",
diff --git a/R/scale_color_okabeito.R b/R/scale_color_okabeito.R
index e72db7b3b..5480e4d8b 100644
--- a/R/scale_color_okabeito.R
+++ b/R/scale_color_okabeito.R
@@ -21,9 +21,10 @@
 #' the original yellow color suggested by Okabe and Ito (`"#F0E442"`), use
 #' palettes `"full_original"` or `"black_first_original"`.
 #'
-#' The Okabe-Ito palette is only available as a discrete palette. For
-#' color-accessible continuous variables, consider [the viridis
-#' palettes][ggplot2::scale_colour_viridis_d()].
+#' The Okabe-Ito palette is only available as a discrete palette.
+#' For color-accessible continuous variables, consider
+#' [Paul Tol's palettes][scale_color_tol_discrete()] or
+#' [the viridis palettes][ggplot2::scale_colour_viridis_d()].
 #'
 #' @inheritParams palette_okabeito
 #' @inheritParams scale_color_flat
@@ -120,6 +121,7 @@ scale_fill_oi <- scale_fill_okabeito
 # Palette --------------------------------------------------------------------
 
 # The palette from: https://jfly.uni-koeln.de/color/#pallet
+# or grDevices::palette.colors()
 okabeito_colors_list <- c(
   orange = "#E69F00",
   `light blue` = "#56B4E9",
@@ -147,11 +149,11 @@ okabeito_colors_list <- c(
 #' @inheritParams flat_colors
 #' @param original_names Logical. Should the colors be named using the original
 #'   names used by Okabe and Ito (2008), such as "vermillion" (`TRUE`), or
-#'   simplified names, such as "red" (`FALSE`, default)?
-#'   Only used if no colors are specified (to see all available colors).
-#' @param black_first Logical. Should black be first (`TRUE`) or last (`FALSE`, default)
-#'   in the color palette? Only used if no colors are specified (to see all
-#'   available colors).
+#'   simplified names, such as "red" (`FALSE`, default)? Only used if no colors
+#'   are specified (to see all available colors).
+#' @param black_first Logical. Should black be first (`TRUE`) or last (`FALSE`,
+#'   default) in the color palette? Only used if no colors are specified (to see
+#'   all available colors).
 #' @param amber If amber color should replace yellow in the palette.
 #'
 #' @return A character vector with color-codes.
@@ -226,7 +228,7 @@ okabeito_palettes <- list(
 
 #' Okabe-Ito color palette
 #'
-#' The palette based proposed by Okabe and Ito (2008).
+#' The palette based on Okabe and Ito (2008).
 #'
 #' @inheritParams palette_flat
 #' @param order A vector of numbers from 1 to 9 indicating the order of colors to use
@@ -238,7 +240,7 @@ okabeito_palettes <- list(
 #' https://jfly.uni-koeln.de/color/#pallet (Original work published 2002)
 #'
 #' @details This function is usually not called directly, but from within
-#'   [`scale_color_material()`][scale_color_material].
+#'   [`scale_color_okabeito()`][scale_color_okabeito].
 #'
 #' @export
 palette_okabeito <- function(
diff --git a/R/scale_color_pizza.R b/R/scale_color_pizza.R
index 7713c3d9a..c244d6cb4 100644
--- a/R/scale_color_pizza.R
+++ b/R/scale_color_pizza.R
@@ -210,7 +210,7 @@ pizza_palettes <- list(
 #' @param palette Pizza type. Can be `"margherita"` (default), `"margherita crust"`,
 #' `"diavola"` or `"diavola crust"`.
 #' @param reverse Boolean indicating whether the palette should be reversed.
-#' @param ... Additional arguments to pass to [`colorRampPalette()`][colorRampPalette].
+#' @param ... Additional arguments to pass to [`grDevices::colorRampPalette()`].
 #'
 #' @details This function is usually not called directly, but from within
 #'   [`scale_color_pizza()`][scale_color_pizza].
diff --git a/R/scale_color_tol.R b/R/scale_color_tol.R
new file mode 100644
index 000000000..1b3c3b2a7
--- /dev/null
+++ b/R/scale_color_tol.R
@@ -0,0 +1,241 @@
+#' Paul Tol discrete/qualitative color palettes
+#'
+#' Tol (2021) presents a series of palettes built with mathematical principles
+#' that are appropriate for diverse types of data. The colors in these schemes
+#' are:
+#' - Visually distinct for all people, including viewers with color vision
+#'   deficiencies
+#' - Distinct from black and white
+#' - Distinct on screen and paper,
+#' - Cohesive; that is, they match well together
+#'
+#' Tol provides palettes appropriate to the 3 main types of data:
+#' 1. Qualitative data – nominal or categorical data, where magnitude
+#'    differences are not relevant.
+#' 2. Diverging data – data ordered between two extremes where the midpoint is
+#'    important.
+#' 3. Sequential data – data ordered from low to high.
+#'
+#' This function provides the qualitative palettes, as well as discrete rainbow
+#' sequential palettes. Available palettes for each type of data are:
+#' - Qualitative: `bright`, `high-contrast`, `vibrant`, `muted`,
+#'   `medium-contrast`, `pale`, `dark`, `light`, `ground_cover`
+#' - Diverging: `sunset`, `nightfall`, `BuRd`, `PRGn`
+#' - Sequential: `YlOrBr`, `iridescent`, `rainbow_discrete`, `rainbow_smooth`
+#'
+#' <!-- For rainbow_discrete, pick the optimal set based on the number of colors,
+#'      For rainbow_smooth, include a range argument with examples to start/end at off-white vs. purple, red vs brown
+#'      -->
+#'
+#' <!-- put a table with recommended uses here -->
+#'
+#' ## Colors for missing or invalid data
+#'
+#' A useful feature of Tol's diverging and sequential palettes is that he
+#' provides a recommended color to use for data that fall outside the data range
+#' represented by the color scale (e.g., for invalid or missing data). These
+#' colors are chosen to be highly distinct from the main color palette.
+#'
+#' @inheritParams palette_tol_discrete
+#' @inheritParams scale_color_flat
+#'
+#' @references
+#' Tol, P. (2021). Colour schemes (SRON/EPS Technical Note No. 09-002; Version 3.2).
+#' SRON. https://personal.sron.nl/~pault/data/colourschemes.pdf (Original work published 2009)
+#'
+#' @examples
+#' library(ggplot2)
+#' library(see)
+#'
+#' ggplot(iris, aes(x = Species, y = Sepal.Length, fill = Species)) +
+#'   geom_boxplot() +
+#'   theme_modern() +
+#'   scale_fill_okabeito()
+#'
+#' ggplot(iris, aes(x = Species, y = Sepal.Length, fill = Species)) +
+#'   geom_violin() +
+#'   theme_modern() +
+#'   scale_fill_oi(palette = "black_first")
+#'
+#' # for the original brighter yellow color suggested by Okabe and Ito
+#' ggplot(iris, aes(x = Species, y = Sepal.Length, fill = Species)) +
+#'   geom_violin() +
+#'   theme_modern() +
+#'   scale_fill_oi(palette = "full")
+#'
+#' ggplot(iris, aes(x = Species, y = Sepal.Length, fill = Species)) +
+#'   geom_violin() +
+#'   theme_modern() +
+#'   scale_fill_oi(order = c(1, 5, 6, 2, 4, 3, 7))
+#' @export
+scale_color_tol_discrete <- function(palette = "bright", reverse = FALSE, order = NULL, aesthetics = "color", ...) {
+  discrete_scale(
+    aesthetics = aesthetics,
+    palette = palette_tol_discrete(palette = palette, reverse = reverse, order = order),
+    ...
+  )
+}
+
+# Fill --------------------------------------------------------------------
+
+#' @rdname scale_color_tol_discrete
+#' @export
+scale_fill_tol_discrete <- function(palette = "bright", reverse = FALSE, order = NULL, aesthetics = "fill", ...) {
+  discrete_scale(
+    aesthetics = aesthetics,
+    palette = palette_tol_discrete(palette = palette, reverse = reverse, order = order),
+    ...
+  )
+}
+
+# Aliases -----------------------------------------------------------------
+
+#' @rdname scale_color_tol_discrete
+#' @export
+scale_colour_tol_discrete <- scale_color_tol_discrete
+
+
+# Palette --------------------------------------------------------------------
+
+tol_colors_discrete_list <- list(
+  bright = c(blue = "#4477AA", red = "#EE6677", green = "#228833", yellow = "#CCBB44", cyan = "#66CCEE", purple = "#AA3377", grey = "#BBBBBB"),
+  `high-contrast` = c(blue = "#004488", yellow = "#DDAA33", red = "#BB5566", black = "#000000", white = "#FFFFFF"),
+  vibrant = c(orange = "#EE7733", blue = "#0077BB", cyan = "#33BBEE", magenta = "#EE3377", red = "#CC3311", teal = "#009988", grey = "#BBBBBB"),
+  muted = c(rose = "#CC6677", indigo = "#332288", sand = "#DDCC77", green = "#117733", cyan = "#88CCEE", wine = "#882255", teal = "#44AA99", olive = "#999933", purple = "#AA4499", grey = "#DDDDDD"),
+  `medium-contrast` = c("light blue" = "#6699CC", "dark blue" = "#004488", "light yellow" = "#EECC66", "dark red" = "#994455", "dark yellow" = "#997700", "light red" = "#EE99AA", black = "#000000", white = "#FFFFFF"),
+  pale = c(blue = "#BBCCEE", cyan = "#CCEEFF", green = "#CCDDAA", yellow = "#EEEEBB", red = "#FFCCCC", grey = "#DDDDDD"),
+  dark = c(blue = "#222255", cyan = "#225555", green = "#225522", yellow = "#666633", red = "#663333", grey = "#555555"),
+  light = c(blue = "#77AADD", orange = "#EE8866", yellow = "#EEDD88", pink = "#FFAABB", cyan = "#99DDFF", mint = "#44BB99", pear = "#BBCC33", olive = "#AAAA00", grey = "#DDDDDD"),
+  # TODO: Finish rainbow color schemes
+  rainbow14 = c("3" = "#D1BBD7", "6" = "#AE76A3", "9" = "#882E72", "10" = "#1965B0", "12" = "#5289C7", "14" = "#7BAFDE", "15" = "#4EB265", "16" = "#90C987", "17" = "#CAE0AB", "18" = "#F7F056", "20" = "#F6C141", "22" = "#F1932D", "24" = "#E8601C", "26" = "#DC050C", grey = "#777777"),
+  rainbow23 = c("1" = "#E8ECFB", "2" = "#D9CCE3", "4" = "#CAACCB", "5" = "#BA8DB4", "7" = "#AA6F9E", "8" = "#994F88", "9" = "#882E72", "10" = "#1965B0", "11" = "#437DBF", "13" = "#6195CF", "14" = "#7BAFDE", "15" = "#4EB265", "16" = "#90C987", "17" = "#CAE0AB", "18" = "#F7F056", "19" = "#F7CB45", "21" = "#F4A736", "23" = "#EE8026", "25" = "#E65518", "26" = "#DC050C", "27" = "#A5170E", "28" = "#72190E", "29" = "#42150A", grey = "#777777"),
+  rainbow_all = c("1" = "#E8ECFB", "2" = "#D9CCE3", "3" = "#D1BBD7", "4" = "#CAACCB", "5" = "#BA8DB4", "6" = "#AE76A3", "7" = "#AA6F9E", "8" = "#994F88", "9" = "#882E72", "10" = "#1965B0", "11" = "#437DBF", "12" = "#5289C7", "13" = "#6195CF", "14" = "#7BAFDE", "15" = "#4EB265", "16" = "#90C987", "17" = "#CAE0AB", "18" = "#F7F056", "19" = "#F7CB45", "20" = "#F6C141", "21" = "#F4A736", "22" = "#F1932D", "23" = "#EE8026", "24" = "#E8601C", "25" = "#E65518", "26" = "#DC050C", "27" = "#A5170E", "28" = "#72190E", "29" = "#42150A", "grey" = "#777777"),
+  ground_cover = c(
+    water = "#5566AA", "evergreen needleleaf forest" = "#117733", "deciduous needleleaf forest" = "#44AA66",
+    "mixed forest" = "#55AA22", "evergreen broadleaf forest" = "#668822", "deciduous broadleaf forest" = "#88BB55",
+    woodland = "#558877", "wooded grassland" = "#88BBAA", grassland = "#AADDCC", cropland = "#44AA88",
+    "closed shrubland" = "#DDCC66", "open shrubland" = "#FFDD44", "bare ground" = "#FFEE88", "urband and built up" = "#BB0011"
+  )
+)
+
+#TODO: Add function for rainbow palettes of 1-23
+
+# TODO: Add smooth palettes
+tol_colors_smooth_list <- list(
+  # Diverging
+  sunset = NULL,
+  nightfall = NULL
+  BuRd = NULL,
+  PRGn = NULL,
+  # Sequential
+  YlOrBr = NULL,
+  iridescent = NULL,
+  rainbow = NULL
+)
+
+
+#' Extract Paul Tol colors as hex codes
+#'
+#' Can be used to get the hex code of specific colors from the Paul Tol palettes.
+#' Use `tol_colors()` and specify `palette` to see all available colors.
+#' Note that for sequential palettes, only original (non-interpolated) colors are shown.
+#'
+#' @param ... Character names of colors.
+#' @param palette Character name of palette. Can be:
+#' - Qualitative: `"bright"`, `"high-contrast"`, `"vibrant"`, `"muted"`,`
+#'   "medium-contrast"`, `"pale"`, `"dark"`, `"light"`, `"ground_cover"`
+#' - Diverging: `"sunset"`, `"nightfall"`, `"BuRd"`, `"PRGn"`
+#' - Sequential: `"YlOrBr"`, `"iridescent"`, `"rainbow_discrete"`,
+#'   `"rainbow_smooth"`
+#'
+#' @return A character vector with color-codes.
+#'
+#' @examples
+#' tol_colors()
+#'
+#' tol_colors(c("red", "light blue", "yellow"))
+#'
+#' tol_colors(palette = "muted")
+#'
+#' tol_colors(c("red", "light blue", "yellow"), palette = "muted")
+#' @export
+tol_colors <- function(..., palette = "bright") {
+  cols <- c(...)
+
+  # TODO: Extract Tol palettes instead of O-I
+  if (!is.null(cols)) {
+    return(okabeito_colors_list[cols])
+  }
+
+  yellow_col <- if (isTRUE(amber)) "amber" else "yellow"
+
+  if (isTRUE(original_names)) {
+    cols <- c("orange", "sky blue", "bluish green", yellow_col, "blue", "vermillion", "reddish purple", "grey", "black")
+  } else {
+    cols <- c("orange", "light blue", "green", yellow_col, "blue", "red", "purple", "grey", "black")
+  }
+
+  if (isTRUE(black_first)) cols <- union("black", cols)
+
+  okabeito_colors_list[cols]
+}
+
+
+#' Paul Tol's color palettes
+#'
+#' The palettes proposed by Tol (2021).
+#'
+#' @param palette Character name of palette. Can be:
+#' - Qualitative: `"bright"`, `"high-contrast"`, `"vibrant"`, `"muted"`,
+#'   `"medium-contrast"`, `"pale"`, `"dark"`, `"light"`, `"ground_cover"`
+#' - Diverging: `"sunset"`, `"nightfall",` `"BuRd"`, `"PRGn"`
+#' - Sequential: `"YlOrBr"`, `"iridescent"`, `"rainbow_discrete"`,
+#' - `"rainbow_smooth"`
+#' @param reverse Boolean indicating whether the palette should be reversed.
+#' @param order A vector of numbers indicating the order of colors to use
+#' (default: `NULL` indicating to use all available colors in order).
+#' @param ... For sequential palettes other than `rainbow_discrete`, additional
+#' arguments to pass to [`grDevices::colorRampPalette()`].
+#'
+#' @references
+#' Tol, P. (2021). Colour schemes (SRON/EPS Technical Note No. 09-002; Version 3.2).
+#' SRON. https://personal.sron.nl/~pault/data/colourschemes.pdf (Original work published 2009)
+#'
+#' @details This function is usually not called directly, but from within
+#' [`scale_color_tol()`].
+#'
+#' @export
+palette_tol_discrete <- function(palette = "bright", reverse = FALSE, order = NULL, ...) {
+  if (!palette %in% names(tol_palettes)) {
+    msg <- c(paste0(
+      "Palette name not available. `palette` must be one of ",
+      datawizard::text_concatenate(names(okabeito_palettes), last = " or ", enclose = "`"),
+      "."
+    ), "Using default palette now.")
+    insight::format_warning(msg)
+    palette <- "full"
+  }
+
+  # TODO: Extract Tol palettes instead of O-I
+  pal <- okabeito_palettes[[palette]]
+
+  stopifnot(
+    "`order` must be a vector of integers." = is.numeric(order),
+    "All elements of `order` must be greater than 0 and less than 23." = all(order > 0 & order <= 23)
+  )
+  pal <- pal[order]
+
+  if (reverse) pal <- rev(pal)
+
+  function(n) {
+    if (n > length(pal)) {
+      insight::format_warning(
+        "The number of colors requested `n` is too large.",
+        paste0("The maximum number of colors is ", length(pal), "."),
+        paste0("Returning a palette with ", length(pal), " colors.")
+      )
+      n <- length(pal)
+    }
+    unname(pal[seq_len(n)])
+  }
+}
diff --git a/inst/WORDLIST b/inst/WORDLIST
index d72b33ba7..fbff23c39 100644
--- a/inst/WORDLIST
+++ b/inst/WORDLIST
@@ -25,8 +25,12 @@ ORCID
 Okabe
 Polychoric
 Québec
+SEM
+SRON
 Shachar
 Tetrachoric
+Tol
+Tol's
 UI
 Université
 VIF
@@ -87,6 +91,9 @@ qq
 qqplotr
 rOpenSci
 rstanarm
+sjPlot
+strengejacke
+sron
 subfigures
 ui
 unmapped
diff --git a/man/okabeito_colors.Rd b/man/okabeito_colors.Rd
index 9ed503327..a936dccd7 100644
--- a/man/okabeito_colors.Rd
+++ b/man/okabeito_colors.Rd
@@ -14,12 +14,12 @@ oi_colors(..., original_names = FALSE, black_first = FALSE, amber = TRUE)
 
 \item{original_names}{Logical. Should the colors be named using the original
 names used by Okabe and Ito (2008), such as "vermillion" (\code{TRUE}), or
-simplified names, such as "red" (\code{FALSE}, default)?
-Only used if no colors are specified (to see all available colors).}
+simplified names, such as "red" (\code{FALSE}, default)? Only used if no colors
+are specified (to see all available colors).}
 
-\item{black_first}{Logical. Should black be first (\code{TRUE}) or last (\code{FALSE}, default)
-in the color palette? Only used if no colors are specified (to see all
-available colors).}
+\item{black_first}{Logical. Should black be first (\code{TRUE}) or last (\code{FALSE},
+default) in the color palette? Only used if no colors are specified (to see
+all available colors).}
 
 \item{amber}{If amber color should replace yellow in the palette.}
 }
diff --git a/man/palette_bluebrown.Rd b/man/palette_bluebrown.Rd
index 22067b76f..bc6cd8b11 100644
--- a/man/palette_bluebrown.Rd
+++ b/man/palette_bluebrown.Rd
@@ -18,7 +18,7 @@ respectively.}
 
 \item{reverse}{Boolean indicating whether the palette should be reversed.}
 
-\item{...}{Additional arguments to pass to \code{\link[=colorRampPalette]{colorRampPalette()}}.}
+\item{...}{Additional arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
 }
 \description{
 The palette based on blue-brown colors.
diff --git a/man/palette_colorhex.Rd b/man/palette_colorhex.Rd
index d140b42b9..932b8f912 100644
--- a/man/palette_colorhex.Rd
+++ b/man/palette_colorhex.Rd
@@ -13,7 +13,7 @@ For example, \code{1014416} for the
 
 \item{reverse}{Boolean indicating whether the palette should be reversed.}
 
-\item{...}{Additional arguments to pass to \code{\link[=colorRampPalette]{colorRampPalette()}}.}
+\item{...}{Additional arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
 }
 \description{
 This function downloads a requested color palette from \url{https://www.color-hex.com/}.
diff --git a/man/palette_flat.Rd b/man/palette_flat.Rd
index 64bf80722..23e91d793 100644
--- a/man/palette_flat.Rd
+++ b/man/palette_flat.Rd
@@ -18,7 +18,7 @@ respectively.}
 
 \item{reverse}{Boolean indicating whether the palette should be reversed.}
 
-\item{...}{Additional arguments to pass to \code{\link[=colorRampPalette]{colorRampPalette()}}.}
+\item{...}{Additional arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
 }
 \description{
 The palette based on \href{https://materialui.co/flatuicolors}{Flat UI}.
diff --git a/man/palette_material.Rd b/man/palette_material.Rd
index eb3a4f8ae..2e03cafa6 100644
--- a/man/palette_material.Rd
+++ b/man/palette_material.Rd
@@ -18,7 +18,7 @@ respectively.}
 
 \item{reverse}{Boolean indicating whether the palette should be reversed.}
 
-\item{...}{Additional arguments to pass to \code{\link[=colorRampPalette]{colorRampPalette()}}.}
+\item{...}{Additional arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
 }
 \description{
 The palette based on \href{https://materialui.co/}{material design colors}.
diff --git a/man/palette_metro.Rd b/man/palette_metro.Rd
index cf1be7a02..6c7f0c209 100644
--- a/man/palette_metro.Rd
+++ b/man/palette_metro.Rd
@@ -18,7 +18,7 @@ respectively.}
 
 \item{reverse}{Boolean indicating whether the palette should be reversed.}
 
-\item{...}{Additional arguments to pass to \code{\link[=colorRampPalette]{colorRampPalette()}}.}
+\item{...}{Additional arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
 }
 \description{
 The palette based on \href{https://materialui.co/metrocolors}{Metro colors}.
diff --git a/man/palette_okabeito.Rd b/man/palette_okabeito.Rd
index 119ceecb8..e382d11d1 100644
--- a/man/palette_okabeito.Rd
+++ b/man/palette_okabeito.Rd
@@ -24,14 +24,14 @@ respectively.}
 \item{order}{A vector of numbers from 1 to 9 indicating the order of colors to use
 (default: \code{1:9})}
 
-\item{...}{Additional arguments to pass to \code{\link[=colorRampPalette]{colorRampPalette()}}.}
+\item{...}{Additional arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
 }
 \description{
-The palette based proposed by Okabe and Ito (2008).
+The palette based on Okabe and Ito (2008).
 }
 \details{
 This function is usually not called directly, but from within
-\code{\link[=scale_color_material]{scale_color_material()}}.
+\code{\link[=scale_color_okabeito]{scale_color_okabeito()}}.
 }
 \references{
 Okabe, M., & Ito, K. (2008). Color universal design (CUD):
diff --git a/man/palette_pizza.Rd b/man/palette_pizza.Rd
index 66f26fa06..824d3bfb0 100644
--- a/man/palette_pizza.Rd
+++ b/man/palette_pizza.Rd
@@ -12,7 +12,7 @@ palette_pizza(palette = "margherita", reverse = FALSE, ...)
 
 \item{reverse}{Boolean indicating whether the palette should be reversed.}
 
-\item{...}{Additional arguments to pass to \code{\link[=colorRampPalette]{colorRampPalette()}}.}
+\item{...}{Additional arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
 }
 \description{
 The palette based on authentic neapolitan pizzas.
diff --git a/man/palette_see.Rd b/man/palette_see.Rd
index a39189e64..05fe67bdf 100644
--- a/man/palette_see.Rd
+++ b/man/palette_see.Rd
@@ -18,7 +18,7 @@ respectively.}
 
 \item{reverse}{Boolean indicating whether the palette should be reversed.}
 
-\item{...}{Additional arguments to pass to \code{\link[=colorRampPalette]{colorRampPalette()}}.}
+\item{...}{Additional arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
 }
 \description{
 See design color palette
diff --git a/man/palette_social.Rd b/man/palette_social.Rd
index df841ef50..6740ac372 100644
--- a/man/palette_social.Rd
+++ b/man/palette_social.Rd
@@ -18,7 +18,7 @@ respectively.}
 
 \item{reverse}{Boolean indicating whether the palette should be reversed.}
 
-\item{...}{Additional arguments to pass to \code{\link[=colorRampPalette]{colorRampPalette()}}.}
+\item{...}{Additional arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
 }
 \description{
 The palette based \href{https://materialui.co/socialcolors}{Social colors}.
diff --git a/man/palette_tol_discrete.Rd b/man/palette_tol_discrete.Rd
new file mode 100644
index 000000000..9d4eada6e
--- /dev/null
+++ b/man/palette_tol_discrete.Rd
@@ -0,0 +1,37 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/scale_color_tol.R
+\name{palette_tol_discrete}
+\alias{palette_tol_discrete}
+\title{Paul Tol's color palettes}
+\usage{
+palette_tol_discrete(palette = "bright", reverse = FALSE, order = NULL, ...)
+}
+\arguments{
+\item{palette}{Character name of palette. Can be:
+\itemize{
+\item Qualitative: \code{"bright"}, \code{"high-contrast"}, \code{"vibrant"}, \code{"muted"},
+\code{"medium-contrast"}, \code{"pale"}, \code{"dark"}, \code{"light"}, \code{"ground_cover"}
+\item Diverging: \code{"sunset"}, \code{"BuRd"}, \code{"PRGn"}
+\item Sequential: \code{"YlOrBr"}, \code{"iridescent"}, \code{"rainbow_discrete"},
+\item \code{"rainbow_smooth"}
+}}
+
+\item{reverse}{Boolean indicating whether the palette should be reversed.}
+
+\item{order}{A vector of numbers indicating the order of colors to use
+(default: \code{NULL} indicating to use all available colors in order).}
+
+\item{...}{For sequential palettes other than \code{rainbow_discrete}, additional
+arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
+}
+\description{
+The palettes proposed by Tol (2021).
+}
+\details{
+This function is usually not called directly, but from within
+\code{\link[=scale_color_tol]{scale_color_tol()}}.
+}
+\references{
+Tol, P. (2021). Colour schemes (SRON/EPS Technical Note No. 09-002; Version 3.2).
+SRON. https://personal.sron.nl/~pault/data/colourschemes.pdf (Original work published 2009)
+}
diff --git a/man/scale_color_bluebrown.Rd b/man/scale_color_bluebrown.Rd
index 1b3569466..d88f1ed6b 100644
--- a/man/scale_color_bluebrown.Rd
+++ b/man/scale_color_bluebrown.Rd
@@ -101,7 +101,7 @@ respectively.}
 \item{aesthetics}{A vector of names of the aesthetics that this scale
 should be applied to (e.g., \code{c('color', 'fill')}).}
 
-\item{...}{Additional arguments to pass to \code{\link[=colorRampPalette]{colorRampPalette()}}.}
+\item{...}{Additional arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
 }
 \description{
 A blue-brown color palette. Use \code{scale_color_bluebrown_d()} for
diff --git a/man/scale_color_colorhex.Rd b/man/scale_color_colorhex.Rd
index 261048c82..b810a24dd 100644
--- a/man/scale_color_colorhex.Rd
+++ b/man/scale_color_colorhex.Rd
@@ -96,7 +96,7 @@ For example, \code{1014416} for the
 \item{aesthetics}{A vector of names of the aesthetics that this scale
 should be applied to (e.g., \code{c('color', 'fill')}).}
 
-\item{...}{Additional arguments to pass to \code{\link[=colorRampPalette]{colorRampPalette()}}.}
+\item{...}{Additional arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
 }
 \description{
 This function creates color scales based on palettes from \url{https://www.color-hex.com/}.
diff --git a/man/scale_color_material.Rd b/man/scale_color_material.Rd
index e6a09d35e..ddcce642d 100644
--- a/man/scale_color_material.Rd
+++ b/man/scale_color_material.Rd
@@ -101,7 +101,7 @@ respectively.}
 \item{aesthetics}{A vector of names of the aesthetics that this scale
 should be applied to (e.g., \code{c('color', 'fill')}).}
 
-\item{...}{Additional arguments to pass to \code{\link[=colorRampPalette]{colorRampPalette()}}.}
+\item{...}{Additional arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
 }
 \description{
 The palette based on \href{https://materialui.co/}{material design colors}. Use
diff --git a/man/scale_color_metro.Rd b/man/scale_color_metro.Rd
index 46f292641..40ea6bcfb 100644
--- a/man/scale_color_metro.Rd
+++ b/man/scale_color_metro.Rd
@@ -101,7 +101,7 @@ respectively.}
 \item{aesthetics}{A vector of names of the aesthetics that this scale
 should be applied to (e.g., \code{c('color', 'fill')}).}
 
-\item{...}{Additional arguments to pass to \code{\link[=colorRampPalette]{colorRampPalette()}}.}
+\item{...}{Additional arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
 }
 \description{
 The palette based on Metro \href{https://materialui.co/metrocolors}{Metro colors}.
diff --git a/man/scale_color_okabeito.Rd b/man/scale_color_okabeito.Rd
index 3b16042ec..3625b525b 100644
--- a/man/scale_color_okabeito.Rd
+++ b/man/scale_color_okabeito.Rd
@@ -75,7 +75,7 @@ respectively.}
 \item{aesthetics}{A vector of names of the aesthetics that this scale
 should be applied to (e.g., \code{c('color', 'fill')}).}
 
-\item{...}{Additional arguments to pass to \code{\link[=colorRampPalette]{colorRampPalette()}}.}
+\item{...}{Additional arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
 }
 \description{
 The Okabe-Ito color palette was proposed by Okabe and Ito (2008) as a
@@ -99,8 +99,10 @@ The palettes \code{"full"} and \code{"black_first"} use this darker yellow color
 the original yellow color suggested by Okabe and Ito (\code{"#F0E442"}), use
 palettes \code{"full_original"} or \code{"black_first_original"}.
 
-The Okabe-Ito palette is only available as a discrete palette. For
-color-accessible continuous variables, consider \link[ggplot2:scale_viridis]{the viridis palettes}.
+The Okabe-Ito palette is only available as a discrete palette.
+For color-accessible continuous variables, consider
+\link[=scale_color_tol_discrete]{Paul Tol's palettes} or
+\link[ggplot2:scale_viridis]{the viridis palettes}.
 }
 \examples{
 library(ggplot2)
diff --git a/man/scale_color_pizza.Rd b/man/scale_color_pizza.Rd
index b88f51be9..3f254ebb7 100644
--- a/man/scale_color_pizza.Rd
+++ b/man/scale_color_pizza.Rd
@@ -95,7 +95,7 @@ scale_fill_pizza_c(
 \item{aesthetics}{A vector of names of the aesthetics that this scale
 should be applied to (e.g., \code{c('color', 'fill')}).}
 
-\item{...}{Additional arguments to pass to \code{\link[=colorRampPalette]{colorRampPalette()}}.}
+\item{...}{Additional arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
 }
 \description{
 The palette based on authentic neapolitan pizzas.
diff --git a/man/scale_color_see.Rd b/man/scale_color_see.Rd
index 5298d921f..05b13bd34 100644
--- a/man/scale_color_see.Rd
+++ b/man/scale_color_see.Rd
@@ -101,7 +101,7 @@ respectively.}
 \item{aesthetics}{A vector of names of the aesthetics that this scale
 should be applied to (e.g., \code{c('color', 'fill')}).}
 
-\item{...}{Additional arguments to pass to \code{\link[=colorRampPalette]{colorRampPalette()}}.}
+\item{...}{Additional arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
 }
 \description{
 The See color palette. Use \code{scale_color_see_d()} for \emph{discrete} categories
diff --git a/man/scale_color_social.Rd b/man/scale_color_social.Rd
index fd7134436..a1ea5e9ba 100644
--- a/man/scale_color_social.Rd
+++ b/man/scale_color_social.Rd
@@ -101,7 +101,7 @@ respectively.}
 \item{aesthetics}{A vector of names of the aesthetics that this scale
 should be applied to (e.g., \code{c('color', 'fill')}).}
 
-\item{...}{Additional arguments to pass to \code{\link[=colorRampPalette]{colorRampPalette()}}.}
+\item{...}{Additional arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
 }
 \description{
 The palette based \href{https://materialui.co/socialcolors}{Social colors}. Use
diff --git a/man/scale_color_tol_discrete.Rd b/man/scale_color_tol_discrete.Rd
new file mode 100644
index 000000000..64ce0c09f
--- /dev/null
+++ b/man/scale_color_tol_discrete.Rd
@@ -0,0 +1,128 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/scale_color_tol.R
+\name{scale_color_tol_discrete}
+\alias{scale_color_tol_discrete}
+\alias{scale_fill_tol_discrete}
+\alias{scale_colour_tol_discrete}
+\title{Paul Tol discrete/qualitative color palettes}
+\usage{
+scale_color_tol_discrete(
+  palette = "bright",
+  reverse = FALSE,
+  order = NULL,
+  aesthetics = "color",
+  ...
+)
+
+scale_fill_tol_discrete(
+  palette = "bright",
+  reverse = FALSE,
+  order = NULL,
+  aesthetics = "fill",
+  ...
+)
+
+scale_colour_tol_discrete(
+  palette = "bright",
+  reverse = FALSE,
+  order = NULL,
+  aesthetics = "color",
+  ...
+)
+}
+\arguments{
+\item{palette}{Character name of palette. Can be:
+\itemize{
+\item Qualitative: \code{"bright"}, \code{"high-contrast"}, \code{"vibrant"}, \code{"muted"},
+\code{"medium-contrast"}, \code{"pale"}, \code{"dark"}, \code{"light"}, \code{"ground_cover"}
+\item Diverging: \code{"sunset"}, \code{"BuRd"}, \code{"PRGn"}
+\item Sequential: \code{"YlOrBr"}, \code{"iridescent"}, \code{"rainbow_discrete"},
+\item \code{"rainbow_smooth"}
+}}
+
+\item{reverse}{Boolean indicating whether the palette should be reversed.}
+
+\item{order}{A vector of numbers indicating the order of colors to use
+(default: \code{NULL} indicating to use all available colors in order).}
+
+\item{aesthetics}{A vector of names of the aesthetics that this scale
+should be applied to (e.g., \code{c('color', 'fill')}).}
+
+\item{...}{For sequential palettes other than \code{rainbow_discrete}, additional
+arguments to pass to \code{\link[grDevices:colorRamp]{grDevices::colorRampPalette()}}.}
+}
+\description{
+Tol (2021) presents a series of palettes built with mathematical principles
+that are appropriate for diverse types of data. The colors in these schemes
+are:
+\itemize{
+\item Visually distinct for all people, including viewers with color vision
+deficiencies
+\item Distinct from black and white
+\item Distinct on screen and paper,
+\item Cohesive; that is, they match well together
+}
+}
+\details{
+Tol provides palettes appropriate to the 3 main types of data:
+\enumerate{
+\item Qualitative data – nominal or categorical data, where magnitude
+differences are not relevant.
+\item Diverging data – data ordered between two extremes where the midpoint is
+important.
+\item Sequential data – data ordered from low to high.
+}
+
+This function provides the qualitative palettes, as well as discrete rainbow
+sequential palettes. Available palettes for each type of data are:
+\itemize{
+\item Qualitative: \code{bright}, \code{high-contrast}, \code{vibrant}, \code{muted},
+\code{medium-contrast}, \code{pale}, \code{dark}, \code{light}, \code{ground_cover}
+\item Diverging: \code{sunset}, \code{BuRd}, \code{PRGn}
+\item Sequential: \code{YlOrBr}, \code{iridescent}, \code{rainbow_discrete}, \code{rainbow_smooth}
+}\if{html}{\out{
+<!-- For rainbow_discrete, pick the optimal set based on the number of colors,
+     For rainbow_smooth, include a range argument with examples to start/end at off-white vs. purple, red vs brown
+     -->
+}}
+\if{html}{\out{
+<!-- put a table with recommended uses here -->
+}}
+
+\subsection{Colors for missing or invalid data}{
+
+A useful feature of Tol's diverging and sequential palettes is that he
+provides a recommended color to use for data that fall outside the data range
+represented by the color scale (e.g., for invalid or missing data). These
+colors are chosen to be highly distinct from the main color palette.
+}
+}
+\examples{
+library(ggplot2)
+library(see)
+
+ggplot(iris, aes(x = Species, y = Sepal.Length, fill = Species)) +
+  geom_boxplot() +
+  theme_modern() +
+  scale_fill_okabeito()
+
+ggplot(iris, aes(x = Species, y = Sepal.Length, fill = Species)) +
+  geom_violin() +
+  theme_modern() +
+  scale_fill_oi(palette = "black_first")
+
+# for the original brighter yellow color suggested by Okabe and Ito
+ggplot(iris, aes(x = Species, y = Sepal.Length, fill = Species)) +
+  geom_violin() +
+  theme_modern() +
+  scale_fill_oi(palette = "full")
+
+ggplot(iris, aes(x = Species, y = Sepal.Length, fill = Species)) +
+  geom_violin() +
+  theme_modern() +
+  scale_fill_oi(order = c(1, 5, 6, 2, 4, 3, 7))
+}
+\references{
+Tol, P. (2021). Colour schemes (SRON/EPS Technical Note No. 09-002; Version 3.2).
+SRON. https://personal.sron.nl/~pault/data/colourschemes.pdf (Original work published 2009)
+}
diff --git a/man/tol_colors.Rd b/man/tol_colors.Rd
new file mode 100644
index 000000000..a8859a00a
--- /dev/null
+++ b/man/tol_colors.Rd
@@ -0,0 +1,36 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/scale_color_tol.R
+\name{tol_colors}
+\alias{tol_colors}
+\title{Extract Paul Tol colors as hex codes}
+\usage{
+tol_colors(..., palette = "bright")
+}
+\arguments{
+\item{...}{Character names of colors.}
+
+\item{palette}{Character name of palette. Can be:
+\itemize{
+\item Qualitative: \code{"bright"}, \code{"high-contrast"}, \code{"vibrant"}, \code{"muted"},\code{ "medium-contrast"}, \code{"pale"}, \code{"dark"}, \code{"light"}, \code{"ground_cover"}
+\item Diverging: \code{"sunset"}, \code{"BuRd"}, \code{"PRGn"}
+\item Sequential: \code{"YlOrBr"}, \code{"iridescent"}, \code{"rainbow_discrete"},
+\code{"rainbow_smooth"}
+}}
+}
+\value{
+A character vector with color-codes.
+}
+\description{
+Can be used to get the hex code of specific colors from the Paul Tol palettes.
+Use \code{tol_colors()} and specify \code{palette} to see all available colors.
+Note that for sequential palettes, only original (non-interpolated) colors are shown.
+}
+\examples{
+tol_colors()
+
+tol_colors(c("red", "light blue", "yellow"))
+
+tol_colors(palette = "muted")
+
+tol_colors(c("red", "light blue", "yellow"), palette = "muted")
+}