diff --git a/src/main/scala/com/htmlism/mos6502/dsl/AsmDocumentContext.scala b/src/main/scala/com/htmlism/mos6502/dsl/AsmDocumentContext.scala
index 8b1225d..5526274 100644
--- a/src/main/scala/com/htmlism/mos6502/dsl/AsmDocumentContext.scala
+++ b/src/main/scala/com/htmlism/mos6502/dsl/AsmDocumentContext.scala
@@ -16,6 +16,9 @@ class AsmDocumentContext {
   def push(x: TopLevelAsmDocumentFragment): Unit =
     xs.append(x)
 
+  def attach(sub: Subroutine): Unit =
+    xs.append(sub)
+
   def toDoc: AsmDocument =
     AsmDocument(xs.toList)
 }
@@ -29,6 +32,11 @@ case class AsmFragment(xs: List[Statement]) extends TopLevelAsmDocumentFragment
     xs.map(_.toAsm).mkString("\n")
 }
 
+case class Subroutine(name: String, fragment: AsmFragment) extends TopLevelAsmDocumentFragment {
+  def toAsm: String =
+    name + ":" + "\n" + fragment.toAsm
+}
+
 case class DefinitionGroup(comment: String, xs: List[Definition[_]]) extends TopLevelAsmDocumentFragment {
   def toAsm: String = {
     val commentLine =
diff --git a/src/main/scala/com/htmlism/mos6502/dsl/syntax/AsmSyntax.scala b/src/main/scala/com/htmlism/mos6502/dsl/syntax/AsmSyntax.scala
index cdede0b..3007a02 100644
--- a/src/main/scala/com/htmlism/mos6502/dsl/syntax/AsmSyntax.scala
+++ b/src/main/scala/com/htmlism/mos6502/dsl/syntax/AsmSyntax.scala
@@ -1,8 +1,23 @@
 package com.htmlism.mos6502.dsl
 package syntax
 
+import com.htmlism.mos6502.model._
+
 trait AsmSyntax {
   def label(s: String)(implicit ctx: AssemblyContext): Unit =
     ctx
       .label(s)
+
+  def sub(s: String)(f: AssemblyContext => Unit): Subroutine = {
+    val ctx: AssemblyContext =
+      new AssemblyContext
+
+    f(ctx)
+
+    Subroutine(s, ctx.toFragment)
+  }
+
+  def jump(s: Subroutine)(implicit ctx: AssemblyContext): Unit =
+    ctx
+      .branch(JSR, s.name)
 }
diff --git a/src/test/scala/com/htmlism/mos6502/dsl/Easy6502Spec.scala b/src/test/scala/com/htmlism/mos6502/dsl/Easy6502Spec.scala
index e579519..d8d66ba 100644
--- a/src/test/scala/com/htmlism/mos6502/dsl/Easy6502Spec.scala
+++ b/src/test/scala/com/htmlism/mos6502/dsl/Easy6502Spec.scala
@@ -66,6 +66,26 @@ class Easy6502Spec extends AnyFlatSpec with should.Matchers {
     )
   }
 
+  "sub demo" should "compile" in {
+    val init =
+      sub("init") { implicit a =>
+        registers.X.incr
+      }
+
+    val doc =
+      asmDoc { implicit ctx =>
+        asm { implicit a =>
+          jump(init)
+        }
+
+        ctx.attach(init)
+      }
+
+    println(
+      doc.toAsm
+    )
+  }
+
   def withAssemblyContext(f: AssemblyContext => Unit): AssemblyContext = {
     val ctx: AssemblyContext =
       new AssemblyContext