diff --git a/Sources/Playground.swift b/Sources/Playground.swift
index e95fccc..399ef01 100644
--- a/Sources/Playground.swift
+++ b/Sources/Playground.swift
@@ -24,6 +24,8 @@ public class Playground: Generatable {
     public var autoRun: Bool
     /// The code that the playground should contain (if nil, a default will be used)
     public var code: String?
+    /// The auxiliary source files that the playground should include
+    public var auxiliarySourceFiles = [File]()
 
     // MARK: - Initializer
 
@@ -61,6 +63,8 @@ public class Playground: Generatable {
             let xmlFile = try folder.createFile(named: "contents.xcplayground")
             try xmlFile.write(string: generateXML())
 
+            try copyAuxiliarySourceFiles(into: folder)
+
             let workspace = Workspace(path: path + "playground.xcworkspace")
             workspace.addReference(to: "self:")
             try workspace.generate()
@@ -78,6 +82,18 @@ public class Playground: Generatable {
         xml.append("</playground>")
         return xml
     }
+
+    private func copyAuxiliarySourceFiles(into folder: Folder) throws {
+        guard !auxiliarySourceFiles.isEmpty else {
+            return
+        }
+
+        let sourcesFolder = try folder.createSubfolder(named: "Sources")
+
+        for file in auxiliarySourceFiles {
+            try file.copy(to: sourcesFolder)
+        }
+    }
 }
 
 // MARK: - Private extensions
diff --git a/Tests/XgenTests/XgenTests.swift b/Tests/XgenTests/XgenTests.swift
index 83b24eb..7a74018 100644
--- a/Tests/XgenTests/XgenTests.swift
+++ b/Tests/XgenTests/XgenTests.swift
@@ -116,6 +116,33 @@ class XgenTests: XCTestCase {
         let autoRunAttribute = xml.rootElement()?.attribute(forName: "executeOnSourceChanges")
         XCTAssertEqual(autoRunAttribute?.stringValue, "false")
     }
+
+    func testPlaygroundWithoutAuxiliarySourceFilesDoesNotHaveSourcesFolder() throws {
+        let playground = Playground(path: folder.path + "Playground")
+        try playground.generate()
+
+        let playgroundFolder = try folder.subfolder(named: "Playground.playground")
+        XCTAssertFalse(playgroundFolder.containsSubfolder(named: "Sources"))
+    }
+
+    func testGeneratingPlaygroundWithAuxiliarySourceFiles() throws {
+        let playground = Playground(path: folder.path + "Playground")
+        try playground.auxiliarySourceFiles = [
+            folder.createFile(named: "A.swift", contents: "//A"),
+            folder.createFile(named: "B.swift", contents: "//B")
+        ]
+
+        try playground.generate()
+
+        let playgroundFolder = try folder.subfolder(named: "Playground.playground")
+        let sourcesFolder = try playgroundFolder.subfolder(named: "Sources")
+
+        let sourceFileNames = sourcesFolder.files.map { $0.nameExcludingExtension }
+        XCTAssertEqual(sourceFileNames, ["A", "B"])
+
+        let sources = try sourcesFolder.files.map { try $0.readAsString() }
+        XCTAssertEqual(sources, ["//A", "//B"])
+    }
 }
 
 // MARK: - Extensions