diff --git a/lib/generators/rails/content/templates/model.rb.tt b/lib/generators/rails/content/templates/model.rb.tt
index 92df3d4..f520b63 100644
--- a/lib/generators/rails/content/templates/model.rb.tt
+++ b/lib/generators/rails/content/templates/model.rb.tt
@@ -2,7 +2,7 @@ class Content::<%= class_name %> < Perron::Resource
 <% if data_sources? -%>
   sources <%= data_sources.map { ":#{it}" }.join(", ") %>
 
-  def self.source_template(sources)
+  def self.source_template(source)
     <<~MARKDOWN
     ---
     ---
diff --git a/lib/perron/resource/sourceable.rb b/lib/perron/resource/sourceable.rb
index 351c87a..f8a8b61 100644
--- a/lib/perron/resource/sourceable.rb
+++ b/lib/perron/resource/sourceable.rb
@@ -15,6 +15,18 @@ def source_definitions
           @source_definitions || {}
         end
 
+        def resolve(name)
+          definition = source_definitions[name]
+
+          data = if definition[:class]
+            definition[:class].all
+          else
+            Perron::DataSource.new(name.to_s).to_a
+          end
+
+          definition[:scope] ? definition[:scope].call(data) : data
+        end
+
         def source_names = source_definitions.keys
 
         def generate_from_sources!
@@ -36,20 +48,29 @@ def source_backed? = source_names.any?
         def parsed(*arguments)
           return {} if arguments.empty?
 
-          arguments.flat_map { it.is_a?(Hash) ? it.to_a : [[it, {primary_key: :id}]] }.to_h
+          arguments.flat_map do |argument|
+            case argument
+            when Hash
+              argument.to_a
+            when Proc
+              [[SecureRandom.hex(8).to_sym, {scope: argument, primary_key: :id}]]
+            else
+              [[argument, {primary_key: :id}]]
+            end
+          end.to_h
         end
 
         def combinations
-          datasets = source_names.map { Perron::DataSource.new(it.to_s) }
+          datasets = source_names.map { resolve it }
 
           datasets.first.product(*datasets[1..])
         end
 
         def content_with(combo)
           data = source_names.each.with_index.to_h { |name, index| [name, combo[index]] }
-          sources = Source.new(data)
+          source = Source.new(data)
 
-          source_template(sources)
+          source_template(source)
         end
 
         def filename_with(combo)
@@ -65,21 +86,23 @@ def output_dir = Perron.configuration.input.join(model_name.collection)
 
       def source_backed? = self.class.source_backed?
 
-      def sources
-        @sources ||= begin
+      def source
+        @source ||= begin
           data = self.class.source_definitions.each_with_object({}) do |(name, options), hash|
             primary_key = options[:primary_key]
             singular_name = name.to_s.singularize
             identifier = frontmatter["#{singular_name}_#{primary_key}"]
 
-            hash[name] = Perron::DataSource.new(name.to_s).find { it.public_send(primary_key).to_s == identifier.to_s }
+            dataset = self.class.send(:resolve, name)
+            hash[name] = dataset.find { it.public_send(primary_key).to_s == identifier.to_s }
           end
 
           Source.new(data)
         end
       end
+      alias_method :sources, :source
 
-      def source_template(sources)
+      def source_template(source)
         raise NotImplementedError, "#{self.class.name} must implement #source_template"
       end
 
diff --git a/test/dummy/app/models/content/product.rb b/test/dummy/app/models/content/product.rb
index a7a0334..6194a84 100644
--- a/test/dummy/app/models/content/product.rb
+++ b/test/dummy/app/models/content/product.rb
@@ -1,20 +1,20 @@
 class Content::Product < Perron::Resource
   sources :countries, products: { primary_key: :code }
 
-  def self.source_template(sources)
+  def self.source_template(source)
     <<~TEMPLATE
     ---
-    product_code: #{sources.products.code}
-    country_id: #{sources.countries.id}
-    title: #{sources.products.name} in #{sources.countries.name}
-    slug: #{sources.products.slug}-#{sources.countries.code.downcase}
+    product_code: #{source.products.code}
+    country_id: #{source.countries.id}
+    title: #{source.products.name} in #{source.countries.name}
+    slug: #{source.products.slug}-#{source.countries.code.downcase}
     ---
 
-    # #{sources.products.name}
+    # #{source.products.name}
 
-    Available in #{sources.countries.name} (#{sources.countries.code}) for $#{sources.products.price}.
+    Available in #{source.countries.name} (#{source.countries.code}) for $#{source.products.price}.
 
-    Product code: #{sources.products.code}
+    Product code: #{source.products.code}
     TEMPLATE
   end
 end
diff --git a/test/generators/perron/content_generator_test.rb b/test/generators/perron/content_generator_test.rb
index afef8ff..751a16c 100644
--- a/test/generators/perron/content_generator_test.rb
+++ b/test/generators/perron/content_generator_test.rb
@@ -112,7 +112,7 @@ class ContentGeneratorTest < Rails::Generators::TestCase
     assert_file "app/content/data/products.yml"
 
     assert_file "app/models/content/product.rb", /sources :countries, :products/
-    assert_file "app/models/content/product.rb", /def self\.source_template\(sources\)/
+    assert_file "app/models/content/product.rb", /def self\.source_template\(source\)/
   end
 
   test "--data flag creates data source files with custom extensions" do
diff --git a/test/perron/resource/sourceable_test.rb b/test/perron/resource/sourceable_test.rb
index 2ded5de..588c622 100644
--- a/test/perron/resource/sourceable_test.rb
+++ b/test/perron/resource/sourceable_test.rb
@@ -1,4 +1,5 @@
 require "test_helper"
+require "support/data_api_source"
 
 class Perron::Resource::SourceableTest < ActiveSupport::TestCase
   setup do
@@ -74,4 +75,38 @@ class Perron::Resource::SourceableTest < ActiveSupport::TestCase
 
     assert resource.source_backed?
   end
+
+  test ".sources with custom class uses class.all method" do
+    test_class = Class.new(Perron::Resource) do
+      sources products: { class: DataApiSource }
+
+      def self.source_template(source)
+        "test template"
+      end
+    end
+
+    combinations = test_class.send(:combinations)
+
+    assert_equal 2, combinations.length
+    assert_equal "product-1", combinations.first.first.id
+    assert_equal "product-2", combinations.last.first.id
+  end
+
+  test ".sources with custom class and scope combines both" do
+    test_class = Class.new(Perron::Resource) do
+      sources products: {
+        class: DataApiSource,
+        scope: -> (products) { products.select(&:active) }
+      }
+
+      def self.source_template(source)
+        "test template"
+      end
+    end
+
+    combinations = test_class.send(:combinations)
+
+    assert_equal 1, combinations.length
+    assert_equal "product-1", combinations.first.first.id
+  end
 end
diff --git a/test/support/data_api_source.rb b/test/support/data_api_source.rb
new file mode 100644
index 0000000..017a806
--- /dev/null
+++ b/test/support/data_api_source.rb
@@ -0,0 +1,16 @@
+class DataApiProduct
+  attr_reader :id, :name, :active
+
+  def initialize(id:, name:, active:)
+    @id, @name, @active = id, name, active
+  end
+end
+
+class DataApiSource
+  def self.all
+    [
+      DataApiProduct.new(id: "product-1", name: "API Product 1", active: true),
+      DataApiProduct.new(id: "product-2", name: "API Product 2", active: false)
+    ]
+  end
+end