diff --git a/bridgetown-core/lib/bridgetown-core/collection.rb b/bridgetown-core/lib/bridgetown-core/collection.rb
index 1132a6bf8..e0f5a1526 100644
--- a/bridgetown-core/lib/bridgetown-core/collection.rb
+++ b/bridgetown-core/lib/bridgetown-core/collection.rb
@@ -368,9 +368,12 @@ def read_static_file(file_path, full_path)
     end
 
     def relative_model_path_for(full_path, manifest: nil)
-      Pathname(full_path).relative_path_from(
-        manifest ? Pathname(manifest.content) : Pathname(site.source)
-      ).to_s
+      content_root = if manifest
+                       manifest.contents ? manifest.contents[label.to_sym] : manifest.content
+                     else
+                       site.source
+                     end
+      Pathname(full_path).relative_path_from(content_root).to_s
     end
 
     def model_id_from_relative_path(model_relative_path, manifest: nil)
diff --git a/bridgetown-core/lib/bridgetown-core/commands/plugins.rb b/bridgetown-core/lib/bridgetown-core/commands/plugins.rb
index 0e499aa8d..80d4a8831 100644
--- a/bridgetown-core/lib/bridgetown-core/commands/plugins.rb
+++ b/bridgetown-core/lib/bridgetown-core/commands/plugins.rb
@@ -61,7 +61,9 @@ def list
         site.config.source_manifests.each do |manifest|
           Bridgetown.logger.info("Origin:", (manifest.origin || "n/a").to_s.green)
           Bridgetown.logger.info("Components:", (manifest.components || "n/a").to_s.cyan)
-          Bridgetown.logger.info("Content:", (manifest.content || "n/a").to_s.cyan)
+          Bridgetown.logger.info("Contents:", (
+            manifest.contents&.map { |k, v| "#{v} (#{k})" }&.join(", ") || manifest.content || "n/a"
+          ).to_s.cyan)
           Bridgetown.logger.info("Layouts:", (manifest.layouts || "n/a").to_s.cyan)
 
           Bridgetown.logger.info("", "----")
diff --git a/bridgetown-core/lib/bridgetown-core/configuration.rb b/bridgetown-core/lib/bridgetown-core/configuration.rb
index c50cdbe7d..e2178bb40 100644
--- a/bridgetown-core/lib/bridgetown-core/configuration.rb
+++ b/bridgetown-core/lib/bridgetown-core/configuration.rb
@@ -3,7 +3,8 @@
 module Bridgetown
   # The primary configuration object for a Bridgetown project
   class Configuration < HashWithDotAccess::Hash
-    REQUIRE_DENYLIST = %i(parse_routes ssr) # rubocop:disable Style/MutableConstant
+    # Built-in initializer list which isn't Gem-backed:
+    REQUIRE_DENYLIST = %i(external_sources parse_routes ssr) # rubocop:disable Style/MutableConstant
 
     Initializer = Struct.new(:name, :block, :completed, keyword_init: true) do
       def to_s
@@ -11,7 +12,9 @@ def to_s
       end
     end
 
-    SourceManifest = Struct.new(:origin, :components, :content, :layouts, keyword_init: true)
+    SourceManifest = Struct.new(
+      :origin, :components, :content, :contents, :layouts, keyword_init: true
+    )
 
     Preflight = Struct.new(:source_manifests, :initializers, keyword_init: true) do
       def initialize(*)
diff --git a/bridgetown-core/lib/bridgetown-core/front_matter/defaults.rb b/bridgetown-core/lib/bridgetown-core/front_matter/defaults.rb
index d9041ba99..9b8281ace 100644
--- a/bridgetown-core/lib/bridgetown-core/front_matter/defaults.rb
+++ b/bridgetown-core/lib/bridgetown-core/front_matter/defaults.rb
@@ -16,6 +16,7 @@ def initialize(site)
       def reset
         @glob_cache = {}
         @defaults_cache = {}
+        @sets = nil
       end
 
       def ensure_time!(set)
@@ -185,10 +186,10 @@ def matching_sets(path, collection)
       #
       # @return [Array<Hash>]
       def valid_sets
-        sets = site.config["defaults"]
-        return [] unless sets.is_a?(Array)
+        @sets ||= site.config["defaults"].map { HashWithDotAccess::Hash.new(_1) }
+        return [] unless @sets.is_a?(Array)
 
-        sets.filter_map do |set|
+        @sets.filter_map do |set|
           if valid?(set)
             massage_scope!(set)
             # TODO: is this trip really necessary?
diff --git a/bridgetown-core/lib/bridgetown-core/model/plugin_origin.rb b/bridgetown-core/lib/bridgetown-core/model/plugin_origin.rb
index aef2a6681..5e8b13c7a 100644
--- a/bridgetown-core/lib/bridgetown-core/model/plugin_origin.rb
+++ b/bridgetown-core/lib/bridgetown-core/model/plugin_origin.rb
@@ -27,7 +27,9 @@ def relative_path
       end
 
       def original_path
-        @original_path ||= relative_path.expand_path(manifest.content)
+        @original_path ||= relative_path.expand_path(
+          manifest.dig(:contents, collection.label.to_sym) || manifest.content
+        )
       end
     end
   end
diff --git a/bridgetown-core/lib/bridgetown-core/reader.rb b/bridgetown-core/lib/bridgetown-core/reader.rb
index 639a07a3a..1131b9214 100644
--- a/bridgetown-core/lib/bridgetown-core/reader.rb
+++ b/bridgetown-core/lib/bridgetown-core/reader.rb
@@ -20,7 +20,7 @@ def read
       read_includes
       sort_files!
       read_collections
-      site.config.source_manifests.select(&:content).each do |manifest|
+      site.config.source_manifests.each do |manifest|
         PluginContentReader.new(site, manifest).read
       end
     end
@@ -66,7 +66,7 @@ def read_directories(dir = "")
 
       entries = Dir.chdir(base) { filter_entries(Dir.entries("."), base) }
       entries.each do |entry|
-        file_path = @site.in_source_dir(base, entry)
+        file_path = site.in_source_dir(base, entry)
         if File.directory?(file_path)
           entries_dirs << entry
         elsif FrontMatter::Loaders.front_matter?(file_path)
diff --git a/bridgetown-core/lib/bridgetown-core/readers/plugin_content_reader.rb b/bridgetown-core/lib/bridgetown-core/readers/plugin_content_reader.rb
index 9161be68f..0cec4db36 100644
--- a/bridgetown-core/lib/bridgetown-core/readers/plugin_content_reader.rb
+++ b/bridgetown-core/lib/bridgetown-core/readers/plugin_content_reader.rb
@@ -2,19 +2,38 @@
 
 module Bridgetown
   class PluginContentReader
-    attr_reader :site, :manifest, :content_dir
+    attr_reader :site, :manifest, :content_dirs
 
     # @param site [Bridgetown::Site]
     # @param manifest [Bridgetown::Plugin::SourceManifest]
     def initialize(site, manifest)
       @site = site
       @manifest = manifest
-      @content_dir = manifest.content
+      @content_dirs = if manifest.contents
+                        manifest.contents
+                      elsif manifest.content
+                        { pages: manifest.content }
+                      end
       @content_files = Set.new
     end
 
     def read
-      return unless content_dir
+      return if content_dirs.empty?
+
+      content_dirs.each do |collection_name, root|
+        read_content_root collection_name, root
+      end
+    end
+
+    def read_content_root(collection_name, content_dir)
+      collection = site.collections[collection_name]
+      unless collection
+        Bridgetown.logger.warn(
+          "Reading",
+          "Plugin requested missing collection #{collection_name}, cannot continue"
+        )
+        return
+      end
 
       Find.find(content_dir) do |path|
         next if File.directory?(path)
@@ -22,17 +41,17 @@ def read
         if File.symlink?(path)
           Bridgetown.logger.warn "Plugin content reader:", "Ignored symlinked asset: #{path}"
         else
-          read_content_file(path)
+          read_content_file(content_dir, path, collection)
         end
       end
     end
 
-    def read_content_file(path)
+    def read_content_file(content_dir, path, collection)
       dir = File.dirname(path.sub("#{content_dir}/", ""))
       name = File.basename(path)
 
       @content_files << if FrontMatter::Loaders.front_matter?(path)
-                          site.collections.pages.read_resource(path, manifest:)
+                          collection.read_resource(path, manifest:)
                         else
                           Bridgetown::StaticFile.new(site, content_dir, "/#{dir}", name)
                         end
diff --git a/bridgetown-core/lib/bridgetown-core/utils/initializers.rb b/bridgetown-core/lib/bridgetown-core/utils/initializers.rb
index 51efea836..84abb4481 100644
--- a/bridgetown-core/lib/bridgetown-core/utils/initializers.rb
+++ b/bridgetown-core/lib/bridgetown-core/utils/initializers.rb
@@ -1,5 +1,8 @@
 # frozen_string_literal: true
 
+# Make sure you update REQUIRE_DENYLIST in `Bridgetown::Configuration` for initializers which
+# aren't Gem backed
+
 Bridgetown.initializer :dotenv do |config|
   Bridgetown.load_dotenv root: config.root_dir
 end
@@ -10,6 +13,15 @@
   end
 end
 
+Bridgetown.initializer :external_sources do |config, contents:|
+  Bridgetown::ExternalSources = Module.new
+
+  config.source_manifest(
+    origin: Bridgetown::ExternalSources,
+    contents:
+  )
+end
+
 Bridgetown.initializer :parse_routes do |config|
   # This builds upon the work done here:
   # https://github.com/jeremyevans/roda-route_list/blob/master/bin/roda-parse_routes