diff --git a/DESCRIPTION b/DESCRIPTION
index 77cb1ce98d..e90be52897 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -40,6 +40,7 @@ Imports:
     MASS,
     mgcv,
     rlang (>= 1.1.0),
+    S7,
     scales (>= 1.2.0),
     stats,
     tibble,
@@ -90,6 +91,7 @@ Collate:
     'compat-plyr.R'
     'utilities.R'
     'aes.R'
+    'all-classes.R'
     'utilities-checks.R'
     'legend-draw.R'
     'geom-.R'
@@ -196,9 +198,9 @@ Collate:
     'margins.R'
     'performance.R'
     'plot-build.R'
+    'plot.R'
     'plot-construction.R'
     'plot-last.R'
-    'plot.R'
     'position-.R'
     'position-collide.R'
     'position-dodge.R'
diff --git a/NAMESPACE b/NAMESPACE
index c5f5a94219..7dd13e633a 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -51,20 +51,6 @@ S3method(get_alt_text,ggplot_built)
 S3method(get_alt_text,gtable)
 S3method(ggplot,"function")
 S3method(ggplot,default)
-S3method(ggplot_add,"NULL")
-S3method(ggplot_add,"function")
-S3method(ggplot_add,Coord)
-S3method(ggplot_add,Facet)
-S3method(ggplot_add,Guides)
-S3method(ggplot_add,Layer)
-S3method(ggplot_add,Scale)
-S3method(ggplot_add,by)
-S3method(ggplot_add,data.frame)
-S3method(ggplot_add,default)
-S3method(ggplot_add,labels)
-S3method(ggplot_add,list)
-S3method(ggplot_add,theme)
-S3method(ggplot_add,uneval)
 S3method(ggplot_build,ggplot)
 S3method(ggplot_gtable,ggplot_built)
 S3method(grid.draw,absoluteGrob)
@@ -228,6 +214,7 @@ export(PositionJitter)
 export(PositionJitterdodge)
 export(PositionNudge)
 export(PositionStack)
+export(S7_ggplot)
 export(Scale)
 export(ScaleBinned)
 export(ScaleBinnedPosition)
diff --git a/R/all-classes.R b/R/all-classes.R
new file mode 100644
index 0000000000..e92f68b185
--- /dev/null
+++ b/R/all-classes.R
@@ -0,0 +1,11 @@
+# Class declarations for S7 dispatch.
+class_theme  <- S7::new_S3_class("theme")
+class_scale  <- S7::new_S3_class("Scale")
+class_labels <- S7::new_S3_class("labels")
+class_guides <- S7::new_S3_class("Guides")
+class_aes    <- S7::new_S3_class("uneval")
+class_coord  <- S7::new_S3_class("Coord")
+class_facet  <- S7::new_S3_class("Facet")
+class_by     <- S7::new_S3_class("by")
+class_layer  <- S7::new_S3_class("Layer")
+class_scales_list <- S7::new_S3_class("ScalesList")
diff --git a/R/plot-construction.R b/R/plot-construction.R
index c4cafd2dc8..6b04a20502 100644
--- a/R/plot-construction.R
+++ b/R/plot-construction.R
@@ -1,3 +1,6 @@
+#' @include plot.R
+NULL
+
 #' Add components to a plot
 #'
 #' `+` is the key to constructing sophisticated ggplot2 graphics. It
@@ -70,7 +73,7 @@ add_ggplot <- function(p, object, objectname) {
   if (is.null(object)) return(p)
 
   p <- plot_clone(p)
-  p <- ggplot_add(object, p, objectname)
+  p <- ggplot_add(object, p, object_name = objectname)
   set_last_plot(p)
   p
 }
@@ -81,105 +84,124 @@ add_ggplot <- function(p, object, objectname) {
 #'
 #' @param object An object to add to the plot
 #' @param plot The ggplot object to add `object` to
-#' @param object_name The name of the object to add
+#' @param ... Additional arguments to pass to the methods. Typically, an
+#'   `object_name` argument that gives a display name for `object` to use
+#'   in error messages.
 #'
 #' @return A modified ggplot object
 #'
 #' @keywords internal
 #' @export
-ggplot_add <- function(object, plot, object_name) {
-  UseMethod("ggplot_add")
-}
-#' @export
-ggplot_add.default <- function(object, plot, object_name) {
-  cli::cli_abort("Can't add {.var {object_name}} to a {.cls ggplot} object.")
-}
-#' @export
-ggplot_add.NULL <- function(object, plot, object_name) {
-  plot
-}
-#' @export
-ggplot_add.data.frame <- function(object, plot, object_name) {
-  plot$data <- object
-  plot
-}
-#' @export
-ggplot_add.function <- function(object, plot, object_name) {
-  cli::cli_abort(c(
-          "Can't add {.var {object_name}} to a {.cls ggplot} object",
-    "i" = "Did you forget to add parentheses, as in {.fn {object_name}}?"
-  ))
-}
-#' @export
-ggplot_add.theme <- function(object, plot, object_name) {
-  plot$theme <- add_theme(plot$theme, object)
-  plot
-}
-#' @export
-ggplot_add.Scale <- function(object, plot, object_name) {
-  plot$scales$add(object)
-  plot
-}
-#' @export
-ggplot_add.labels <- function(object, plot, object_name) {
-  update_labels(plot, object)
-}
-#' @export
-ggplot_add.Guides <- function(object, plot, object_name) {
-  update_guides(plot, object)
-}
-#' @export
-ggplot_add.uneval <- function(object, plot, object_name) {
-  plot$mapping <- defaults(object, plot$mapping)
-  # defaults() doesn't copy class, so copy it.
-  class(plot$mapping) <- class(object)
-
-  labels <- make_labels(object)
-  names(labels) <- names(object)
-  update_labels(plot, labels)
-}
-#' @export
-ggplot_add.Coord <- function(object, plot, object_name) {
-  if (!isTRUE(plot$coordinates$default)) {
-    cli::cli_inform("Coordinate system already present. Adding new coordinate system, which will replace the existing one.")
+ggplot_add <- S7::new_generic("ggplot_add", c("object", "plot"))
+
+S7::method(ggplot_add, list(S7::class_any, S7_ggplot)) <-
+  function(object, plot, object_name) {
+    cli::cli_abort("Can't add {.var {object_name}} to a {.cls ggplot} object.")
   }
 
-  plot$coordinates <- object
-  plot
-}
-#' @export
-ggplot_add.Facet <- function(object, plot, object_name) {
-  plot$facet <- object
-  plot
-}
-#' @export
-ggplot_add.list <- function(object, plot, object_name) {
-  for (o in object) {
-    plot <- plot %+% o
+# Cannot currently double dispatch on NULL directly
+# replace `S7::new_S3_class("NULL")` with `NULL` when S7 version > 0.1.1
+S7::method(ggplot_add, list(S7::new_S3_class("NULL"), S7_ggplot)) <-
+  function(object, plot, object_name) {
+    plot
   }
-  plot
-}
-#' @export
-ggplot_add.by <- function(object, plot, object_name) {
-  ggplot_add.list(object, plot, object_name)
-}
 
-#' @export
-ggplot_add.Layer <- function(object, plot, object_name) {
-  plot$layers <- append(plot$layers, object)
-
-  # Add any new labels
-  mapping <- make_labels(object$mapping)
-  default <- lapply(make_labels(object$stat$default_aes), function(l) {
-    attr(l, "fallback") <- TRUE
-    l
-  })
-  new_labels <- defaults(mapping, default)
-  current_labels <- plot$labels
-  current_fallbacks <- vapply(current_labels, function(l) isTRUE(attr(l, "fallback")), logical(1))
-  plot$labels <- defaults(current_labels[!current_fallbacks], new_labels)
-  if (any(current_fallbacks)) {
-    plot$labels <- defaults(plot$labels, current_labels)
-  }
-  plot
-}
+S7::method(ggplot_add, list(S7::class_data.frame, S7_ggplot)) <-
+  function(object, plot, object_name) {
+    plot$data <- object
+    plot
+  }
+
+S7::method(ggplot_add, list(S7::class_function, S7_ggplot)) <-
+  function(object, plot, object_name) {
+    cli::cli_abort(c(
+      "Can't add {.var {object_name}} to a {.cls ggplot} object",
+      "i" = "Did you forget to add parentheses, as in {.fn {object_name}}?"
+    ))
+  }
+
+S7::method(ggplot_add, list(class_theme, S7_ggplot)) <-
+  function(object, plot, object_name) {
+    plot$theme <- add_theme(plot$theme, object)
+    plot
+  }
+
+S7::method(ggplot_add, list(class_scale, S7_ggplot)) <-
+  function(object, plot, object_name) {
+    plot$scales$add(object)
+    plot
+  }
+
+S7::method(ggplot_add, list(class_labels, S7_ggplot)) <-
+  function(object, plot, object_name) {
+    update_labels(plot, object)
+  }
+
+S7::method(ggplot_add, list(class_guides, S7_ggplot)) <-
+  function(object, plot, object_name) {
+    update_guides(plot, object)
+  }
+
+S7::method(ggplot_add, list(class_aes, S7_ggplot)) <-
+  function(object, plot, object_name) {
+    mapping <- defaults(object, plot$mapping)
+    # defaults() doesn't copy class, so copy it.
+    class(mapping) <- class(object)
+    S7::prop(plot, "mapping") <- mapping
+
+
+    labels <- make_labels(object)
+    names(labels) <- names(object)
+    update_labels(plot, labels)
+  }
+
+S7::method(ggplot_add, list(class_coord, S7_ggplot)) <-
+  function(object, plot, object_name) {
+    if (!isTRUE(plot$coordinates$default)) {
+      cli::cli_inform("Coordinate system already present. Adding new coordinate system, which will replace the existing one.")
+    }
+
+    plot$coordinates <- object
+    plot
+  }
+
+S7::method(ggplot_add, list(class_facet, S7_ggplot)) <-
+  function(object, plot, object_name) {
+    plot$facet <- object
+    plot
+  }
+
+S7::method(ggplot_add, list(S7::class_list, S7_ggplot)) <-
+  function(object, plot, object_name) {
+    for (o in object) {
+      plot <- plot %+% o
+    }
+    plot
+  }
+
+S7::method(ggplot_add, list(class_by, S7_ggplot)) <-
+  function(object, plot, object_name) {
+    S7::method(ggplot_add, list(class_list, ggplot))(
+      object, plot, object_name
+    )
+  }
+
+S7::method(ggplot_add, list(class_layer, S7_ggplot)) <-
+  function(object, plot, object_name) {
+    plot$layers <- append(plot$layers, object)
+
+    # Add any new labels
+    mapping <- make_labels(object$mapping)
+    default <- lapply(make_labels(object$stat$default_aes), function(l) {
+      attr(l, "fallback") <- TRUE
+      l
+    })
+    new_labels <- defaults(mapping, default)
+    current_labels <- plot$labels
+    current_fallbacks <- vapply(current_labels, function(l) isTRUE(attr(l, "fallback")), logical(1))
+    plot$labels <- defaults(current_labels[!current_fallbacks], new_labels)
+    if (any(current_fallbacks)) {
+      plot$labels <- defaults(plot$labels, current_labels)
+    }
+    plot
+  }
diff --git a/R/plot.R b/R/plot.R
index 4494b774bc..818a34ca70 100644
--- a/R/plot.R
+++ b/R/plot.R
@@ -1,3 +1,6 @@
+
+gg <- S7::new_class("gg", abstract = TRUE)
+
 #' Create a new ggplot
 #'
 #' `ggplot()` initializes a ggplot object. It can be used to
@@ -112,25 +115,24 @@ ggplot.default <- function(data = NULL, mapping = aes(), ...,
   if (!missing(mapping) && !inherits(mapping, "uneval")) {
     cli::cli_abort(c(
       "{.arg mapping} should be created with {.fn aes}.",
-      "x" = "You've supplied a {.cls {class(mapping)[1]}} object"
+      "x" = "You've supplied a {.cls {class(mapping)[1]}} object."
     ))
   }
 
   data <- fortify(data, ...)
 
-  p <- structure(list(
-    data = data,
-    layers = list(),
-    scales = scales_list(),
-    guides = guides_list(),
+  p <- S7_ggplot(
+    data    = data,
+    layers  = list(),
+    scales  = scales_list(),
+    guides  = guides_list(),
     mapping = mapping,
-    theme = list(),
+    theme   = theme(),
     coordinates = coord_cartesian(default = TRUE),
-    facet = facet_null(),
+    facet   = facet_null(),
+    labels  = make_labels(mapping),
     plot_env = environment
-  ), class = c("gg", "ggplot"))
-
-  p$labels <- make_labels(mapping)
+  )
 
   set_last_plot(p)
   p
@@ -139,13 +141,73 @@ ggplot.default <- function(data = NULL, mapping = aes(), ...,
 #' @export
 ggplot.function <- function(data = NULL, mapping = aes(), ...,
                             environment = parent.frame()) {
-  # Added to avoid functions end in ggplot.default
   cli::cli_abort(c(
     "{.arg data} cannot be a function.",
-    "i" = "Have you misspelled the {.arg data} argument in {.fn ggplot}"
+    "i" = "Have you misspelled the {.arg data} argument in {.fn ggplot}?"
   ))
 }
 
+#' ggplot class
+#'
+#' The ggplot class is implemented using S7 and has properties needed to
+#' build and render a plot.
+#'
+#' @param data Any object that can be used with [`fortify()`] to yield a
+#'   `<data.frame>`.
+#' @param layers A `<list>` containing `<LayerInstance>` objects. Typically
+#'   an empty `<list>` that will be filled when adding layers using `+`.
+#' @param scales A `<ScalesList>` ggproto object that manages scales that
+#'   are added to the plot.
+#' @param guides A `<Guides>` ggproto object that manages guides that are
+#'   added to the plot.
+#' @param mapping An `<uneval>` object constructed with [`aes()`] containing
+#'   the default aesthetic mappings.
+#' @param theme A `<theme>` object constructed with [`theme()`] containing
+#'   non-data visual settings.
+#' @param coordinates A `<Coord>` ggproto object that manages the interpretation
+#'   of position aesthetics.
+#' @param facet A `<Facet>` ggproto object that manages the display of data
+#'   subsets.
+#' @param labels A named `<list>` of `character`s and `expression`s giving
+#'   aesthetic-label pairs.
+#' @param plot_env An `<environment>` in which the plot was created.
+#'
+#' @details
+#' The purpose of the ggplot class object is to allow developers to extend
+#' their own versions of a ggplot class. Users should instead use the
+#' [`ggplot()`] interface to construct a new plot.
+#'
+#' @export
+S7_ggplot <- S7::new_class(
+  name = "ggplot", parent = gg,
+  properties = list(
+    data        = S7::class_any,
+    layers      = S7::class_list,
+    scales      = class_scales_list,
+    guides      = class_guides,
+    mapping     = class_aes,
+    theme       = class_theme,
+    coordinates = class_coord,
+    facet       = class_facet,
+    labels      = S7::class_list,
+    plot_env    = S7::class_environment
+  )
+)
+
+S7::method(`$`, S7_ggplot) <- function(x, i) {
+  if (!S7::prop_exists(x, i)) {
+    return(NULL)
+  }
+  S7::prop(x, i)
+}
+
+S7::method(`$<-`, S7_ggplot) <- function(x, ...) {
+  S7::`prop<-`(x, ...)
+}
+
+# Deal with S7 bug: https://github.com/RConsortium/S7/issues/390
+rm(`$`, `$<-`)
+
 plot_clone <- function(plot) {
   p <- plot
   p$scales <- plot$scales$clone()
diff --git a/R/zzz.R b/R/zzz.R
index 0dcfd407cf..3158922541 100644
--- a/R/zzz.R
+++ b/R/zzz.R
@@ -30,6 +30,10 @@ on_load(
     vars <- dplyr::vars
   }
 )
+on_load(
+  S7::methods_register()
+)
+
 .onLoad <- function(...) {
   run_on_load()
 }
diff --git a/man/S7_ggplot.Rd b/man/S7_ggplot.Rd
new file mode 100644
index 0000000000..f413d55ce8
--- /dev/null
+++ b/man/S7_ggplot.Rd
@@ -0,0 +1,58 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/plot.R
+\name{S7_ggplot}
+\alias{S7_ggplot}
+\title{ggplot class}
+\usage{
+S7_ggplot(
+  data = class_missing,
+  layers = class_missing,
+  scales = class_missing,
+  guides = class_missing,
+  mapping = class_missing,
+  theme = class_missing,
+  coordinates = class_missing,
+  facet = class_missing,
+  labels = class_missing,
+  plot_env = class_missing
+)
+}
+\arguments{
+\item{data}{Any object that can be used with \code{\link[=fortify]{fortify()}} to yield a
+\verb{<data.frame>}.}
+
+\item{layers}{A \verb{<list>} containing \verb{<LayerInstance>} objects. Typically
+an empty \verb{<list>} that will be filled when adding layers using \code{+}.}
+
+\item{scales}{A \verb{<ScalesList>} ggproto object that manages scales that
+are added to the plot.}
+
+\item{guides}{A \verb{<Guides>} ggproto object that manages guides that are
+added to the plot.}
+
+\item{mapping}{An \verb{<uneval>} object constructed with \code{\link[=aes]{aes()}} containing
+the default aesthetic mappings.}
+
+\item{theme}{A \verb{<theme>} object constructed with \code{\link[=theme]{theme()}} containing
+non-data visual settings.}
+
+\item{coordinates}{A \verb{<Coord>} ggproto object that manages the interpretation
+of position aesthetics.}
+
+\item{facet}{A \verb{<Facet>} ggproto object that manages the display of data
+subsets.}
+
+\item{labels}{A named \verb{<list>} of \code{character}s and \code{expression}s giving
+aesthetic-label pairs.}
+
+\item{plot_env}{An \verb{<environment>} in which the plot was created.}
+}
+\description{
+The ggplot class is implemented using S7 and has properties needed to
+build and render a plot.
+}
+\details{
+The purpose of the ggplot class object is to allow developers to extend
+their own versions of a ggplot class. Users should instead use the
+\code{\link[=ggplot]{ggplot()}} interface to construct a new plot.
+}
diff --git a/man/ggplot_add.Rd b/man/ggplot_add.Rd
index 0bd2e2a698..3986ef2962 100644
--- a/man/ggplot_add.Rd
+++ b/man/ggplot_add.Rd
@@ -4,14 +4,16 @@
 \alias{ggplot_add}
 \title{Add custom objects to ggplot}
 \usage{
-ggplot_add(object, plot, object_name)
+ggplot_add(object, plot, ...)
 }
 \arguments{
 \item{object}{An object to add to the plot}
 
 \item{plot}{The ggplot object to add \code{object} to}
 
-\item{object_name}{The name of the object to add}
+\item{...}{Additional arguments to pass to the methods. Typically, an
+\code{object_name} argument that gives a display name for \code{object} to use
+in error messages.}
 }
 \value{
 A modified ggplot object
diff --git a/tests/testthat/_snaps/plot.md b/tests/testthat/_snaps/plot.md
index 6dd7cfd427..85882c7ccd 100644
--- a/tests/testthat/_snaps/plot.md
+++ b/tests/testthat/_snaps/plot.md
@@ -1,12 +1,12 @@
 # ggplot() throws informative errors
 
     `mapping` should be created with `aes()`.
-    x You've supplied a <character> object
+    x You've supplied a <character> object.
 
 ---
 
     `data` cannot be a function.
-    i Have you misspelled the `data` argument in `ggplot()`
+    i Have you misspelled the `data` argument in `ggplot()`?
 
 # construction have user friendly errors