diff --git a/packages/@glimmer/opcode-compiler/lib/opcode-builder.ts b/packages/@glimmer/opcode-compiler/lib/opcode-builder.ts
index b7bd0924b5..ed325612a4 100644
--- a/packages/@glimmer/opcode-compiler/lib/opcode-builder.ts
+++ b/packages/@glimmer/opcode-compiler/lib/opcode-builder.ts
@@ -882,8 +882,13 @@ export abstract class OpcodeBuilder<Specifier> {
     }
   }
 
+  pushBlockScope(): void {
+    this.push(Op.PushBlockScope);
+  }
+
   pushYieldableBlock(block: Option<CompilableBlock>): void {
     this.pushSymbolTable(block && block.symbolTable);
+    this.pushBlockScope();
     this.pushBlock(block);
   }
 
diff --git a/packages/@glimmer/runtime/lib/compiled/opcodes/-debug-strip.ts b/packages/@glimmer/runtime/lib/compiled/opcodes/-debug-strip.ts
index ef99143a8b..80971fab5d 100644
--- a/packages/@glimmer/runtime/lib/compiled/opcodes/-debug-strip.ts
+++ b/packages/@glimmer/runtime/lib/compiled/opcodes/-debug-strip.ts
@@ -4,6 +4,7 @@ import { Tag, TagWrapper, VersionedPathReference, Reference } from "@glimmer/ref
 import { Arguments } from '../../vm/arguments';
 import { ComponentState } from './component';
 import { ComponentManager } from '../../internal-interfaces';
+import { Scope } from '../../environment';
 import { BlockSymbolTable } from "@glimmer/interfaces";
 import { ICompilableTemplate } from "@glimmer/opcode-compiler";
 
@@ -17,6 +18,8 @@ export const CheckReference: Checker<Reference> =
 
 export const CheckArguments = CheckInstanceof(Arguments);
 
+export const CheckScope = CheckInstanceof(Scope);
+
 export const CheckComponentManager: Checker<ComponentManager> =
   CheckInterface({ getCapabilities: CheckFunction });
 
diff --git a/packages/@glimmer/runtime/lib/compiled/opcodes/component.ts b/packages/@glimmer/runtime/lib/compiled/opcodes/component.ts
index 33ff7ec9fe..d9ff74a117 100644
--- a/packages/@glimmer/runtime/lib/compiled/opcodes/component.ts
+++ b/packages/@glimmer/runtime/lib/compiled/opcodes/component.ts
@@ -20,7 +20,7 @@ import {
   PublicComponentSpec
 } from '../../component/interfaces';
 import { normalizeStringValue } from '../../dom/normalize';
-import { DynamicScope, ScopeBlock, ScopeSlot } from '../../environment';
+import { DynamicScope, ScopeBlock, ScopeSlot, Scope } from '../../environment';
 import { APPEND_OPCODES, UpdatingOpcode } from '../../opcodes';
 import { UNDEFINED_REFERENCE } from '../../references';
 import { UpdatingVM, VM } from '../../vm';
@@ -33,7 +33,7 @@ import { check, expectStackChange, CheckInstanceof, CheckFunction, CheckInterfac
 import { Op, Register } from '@glimmer/vm';
 import { TemplateMeta } from "@glimmer/wire-format";
 import { ATTRS_BLOCK } from '@glimmer/opcode-compiler';
-import { CheckReference, CheckArguments, CheckPathReference, CheckComponentState, CheckCompilableBlock } from './-debug-strip';
+import { CheckReference, CheckArguments, CheckPathReference, CheckComponentState, CheckScope, CheckCompilableBlock } from './-debug-strip';
 
 const ARGS = new Arguments();
 
@@ -441,9 +441,10 @@ APPEND_OPCODES.add(Op.InvokeComponentLayout, vm => {
     let bindBlock = (name: string) => {
       let symbol = symbols.indexOf(name);
       let handle = check(stack.pop(), CheckOr(CheckOption(CheckHandle), CheckOption(CheckCompilableBlock)));
+      let blockScope = check(stack.pop(), CheckOption(CheckScope)) as Option<Scope>; // FIXME(mmun): shouldn't need to cast this
       let table = check(stack.pop(), CheckOption(CheckBlockSymbolTable));
 
-      let block: Option<ScopeBlock> = table ? [handle!, table] : null;
+      let block: Option<ScopeBlock> = table ? [handle!, blockScope!, table] : null;
 
       if (symbol !== -1) {
         scope.bindBlock(symbol + 1, block);
diff --git a/packages/@glimmer/runtime/lib/compiled/opcodes/expressions.ts b/packages/@glimmer/runtime/lib/compiled/opcodes/expressions.ts
index 8996198267..f5d2704205 100644
--- a/packages/@glimmer/runtime/lib/compiled/opcodes/expressions.ts
+++ b/packages/@glimmer/runtime/lib/compiled/opcodes/expressions.ts
@@ -1,7 +1,7 @@
 import { Opaque, Option } from '@glimmer/interfaces';
 import { VersionedPathReference } from '@glimmer/reference';
 import { Op } from '@glimmer/vm';
-import { ScopeBlock } from '../../environment';
+import { Scope, ScopeBlock } from '../../environment';
 import { APPEND_OPCODES } from '../../opcodes';
 import { FALSE_REFERENCE, TRUE_REFERENCE } from '../../references';
 import { PublicVM } from '../../vm';
@@ -9,7 +9,7 @@ import { ConcatReference } from '../expressions/concat';
 import { assert } from "@glimmer/util";
 import { check, expectStackChange, CheckFunction, CheckOption, CheckHandle, CheckBlockSymbolTable, CheckOr } from '@glimmer/debug';
 import { stackAssert } from './assert';
-import { CheckArguments, CheckPathReference, CheckCompilableBlock } from './-debug-strip';
+import { CheckArguments, CheckPathReference, CheckCompilableBlock, CheckScope } from './-debug-strip';
 
 export type FunctionExpression<T> = (vm: PublicVM) => VersionedPathReference<T>;
 
@@ -36,9 +36,10 @@ APPEND_OPCODES.add(Op.SetVariable, (vm, { op1: symbol }) => {
 
 APPEND_OPCODES.add(Op.SetBlock, (vm, { op1: symbol }) => {
   let handle = check(vm.stack.pop(), CheckOr(CheckOption(CheckHandle), CheckCompilableBlock));
+  let scope = check(vm.stack.pop(), CheckScope) as Option<Scope>; // FIXME(mmun): shouldn't need to cast this
   let table = check(vm.stack.pop(), CheckOption(CheckBlockSymbolTable));
 
-  let block: Option<ScopeBlock> = table ? [handle!, table] : null;
+  let block: Option<ScopeBlock> = table ? [handle!, scope!, table] : null;
 
   vm.scope().bindBlock(symbol, block);
 });
@@ -70,14 +71,16 @@ APPEND_OPCODES.add(Op.GetBlock, (vm, { op1: _block }) => {
   let block = vm.scope().getBlock(_block);
 
   if (block) {
+    stack.push(block[2]);
     stack.push(block[1]);
     stack.push(block[0]);
   } else {
     stack.push(null);
     stack.push(null);
+    stack.push(null);
   }
 
-  expectStackChange(vm.stack, 2, 'GetBlock');
+  expectStackChange(vm.stack, 3, 'GetBlock');
 });
 
 APPEND_OPCODES.add(Op.HasBlock, (vm, { op1: _block }) => {
@@ -86,7 +89,9 @@ APPEND_OPCODES.add(Op.HasBlock, (vm, { op1: _block }) => {
 });
 
 APPEND_OPCODES.add(Op.HasBlockParams, (vm) => {
+  // FIXME(mmun): should only need to push the symbol table
   check(vm.stack.pop(), CheckOption(CheckOr(CheckHandle, CheckCompilableBlock)));
+  check(vm.stack.pop(), CheckOption(CheckScope));
   let table = check(vm.stack.pop(), CheckOption(CheckBlockSymbolTable));
 
   assert(table === null || (table && typeof table === 'object' && Array.isArray(table.parameters)), stackAssert('Option<BlockSymbolTable>', table));
diff --git a/packages/@glimmer/runtime/lib/compiled/opcodes/vm.ts b/packages/@glimmer/runtime/lib/compiled/opcodes/vm.ts
index ef38318b66..4a53e84e37 100644
--- a/packages/@glimmer/runtime/lib/compiled/opcodes/vm.ts
+++ b/packages/@glimmer/runtime/lib/compiled/opcodes/vm.ts
@@ -12,12 +12,13 @@ import { initializeGuid, assert } from '@glimmer/util';
 import { expectStackChange, CheckNumber, check, CheckInstanceof, CheckOption, CheckBlockSymbolTable, CheckHandle, CheckPrimitive } from '@glimmer/debug';
 import { stackAssert } from './assert';
 import { APPEND_OPCODES, UpdatingOpcode } from '../../opcodes';
+import { Scope } from '../../environment';
 import { PrimitiveReference } from '../../references';
 import { CompilableTemplate } from '../../syntax/interfaces';
 import { VM, UpdatingVM } from '../../vm';
 import { Arguments } from '../../vm/arguments';
 import { LazyConstants, PrimitiveType } from "@glimmer/program";
-import { CheckReference } from './-debug-strip';
+import { CheckReference, CheckScope } from './-debug-strip';
 
 APPEND_OPCODES.add(Op.ChildScope, vm => vm.pushChildScope());
 
@@ -108,6 +109,11 @@ APPEND_OPCODES.add(Op.PushSymbolTable, (vm, { op1: _table }) => {
   stack.push(vm.constants.getSymbolTable(_table));
 });
 
+APPEND_OPCODES.add(Op.PushBlockScope, (vm) => {
+  let stack = vm.stack;
+  stack.push(vm.scope());
+});
+
 APPEND_OPCODES.add(Op.CompileBlock, vm => {
   let stack = vm.stack;
   let block = stack.pop<Option<CompilableTemplate> | 0>();
@@ -128,6 +134,7 @@ APPEND_OPCODES.add(Op.InvokeYield, vm => {
   let { stack } = vm;
 
   let handle = check(stack.pop(), CheckOption(CheckHandle));
+  let scope = check(stack.pop(), CheckOption(CheckScope)) as Option<Scope>; // FIXME(mmun): shouldn't need to cast this
   let table = check(stack.pop(), CheckOption(CheckBlockSymbolTable));
 
   assert(table === null || (table && typeof table === 'object' && Array.isArray(table.parameters)), stackAssert('Option<BlockSymbolTable>', table));
@@ -139,25 +146,30 @@ APPEND_OPCODES.add(Op.InvokeYield, vm => {
 
     // To balance the pop{Frame,Scope}
     vm.pushFrame();
-    vm.pushCallerScope();
-
+    vm.pushScope(scope!); // Could be null but it doesnt matter as it is immediatelly popped.
     return;
   }
 
-  let locals = table.parameters;
-  let localsCount = locals.length;
+  let invokingScope = scope!;
 
-  vm.pushCallerScope(localsCount > 0);
+  // If necessary, create a child scope
+  {
+    let locals = table.parameters;
+    let localsCount = locals.length;
 
-  let scope = vm.scope();
+    if (localsCount > 0) {
+      invokingScope = invokingScope.child();
 
-  for (let i=0; i<localsCount; i++) {
-    scope.bindSymbol(locals![i], args.at(i));
+      for (let i=0; i<localsCount; i++) {
+        invokingScope.bindSymbol(locals![i], args.at(i));
+      }
+    }
   }
 
   args.clear();
 
   vm.pushFrame();
+  vm.pushScope(invokingScope);
   vm.call(handle!);
 });
 
diff --git a/packages/@glimmer/runtime/lib/environment.ts b/packages/@glimmer/runtime/lib/environment.ts
index dff15a7c29..905a1694c9 100644
--- a/packages/@glimmer/runtime/lib/environment.ts
+++ b/packages/@glimmer/runtime/lib/environment.ts
@@ -28,7 +28,7 @@ import { Simple, RuntimeResolver, BlockSymbolTable, VMHandle } from "@glimmer/in
 import { Component, ComponentManager } from "./internal-interfaces";
 import { Program } from "@glimmer/program";
 
-export type ScopeBlock = [VMHandle | ICompilableTemplate<BlockSymbolTable>, BlockSymbolTable];
+export type ScopeBlock = [VMHandle | ICompilableTemplate<BlockSymbolTable>, Scope, BlockSymbolTable];
 export type ScopeSlot = Option<VersionedPathReference<Opaque>> | Option<ScopeBlock>;
 
 export interface DynamicScope {
diff --git a/packages/@glimmer/runtime/lib/vm/append.ts b/packages/@glimmer/runtime/lib/vm/append.ts
index 2a45c6ec81..dfa81d1fc7 100644
--- a/packages/@glimmer/runtime/lib/vm/append.ts
+++ b/packages/@glimmer/runtime/lib/vm/append.ts
@@ -372,11 +372,6 @@ export default class VM<Specifier> implements PublicVM {
     this.scopeStack.push(this.scope().child());
   }
 
-  pushCallerScope(childScope = false) {
-    let callerScope = expect(this.scope().getCallerScope(), 'pushCallerScope is called when a caller scope is present');
-    this.scopeStack.push(childScope ? callerScope.child() : callerScope);
-  }
-
   pushDynamicScope(): DynamicScope {
     let child = this.dynamicScope().child();
     this.dynamicScopeStack.push(child);
@@ -390,6 +385,10 @@ export default class VM<Specifier> implements PublicVM {
     return scope;
   }
 
+  pushScope(scope: Scope) {
+    this.scopeStack.push(scope);
+  }
+
   popScope() {
     this.scopeStack.pop();
   }
diff --git a/packages/@glimmer/vm/lib/-debug-strip.ts b/packages/@glimmer/vm/lib/-debug-strip.ts
index 987bbc7f4f..3a46e597ee 100644
--- a/packages/@glimmer/vm/lib/-debug-strip.ts
+++ b/packages/@glimmer/vm/lib/-debug-strip.ts
@@ -220,6 +220,11 @@ OPCODE_METADATA(Op.PushSymbolTable, {
   stackChange: 1
 });
 
+OPCODE_METADATA(Op.PushBlockScope, {
+  name: 'PushBlockScope',
+  stackChange: 1
+});
+
 OPCODE_METADATA(Op.CompileBlock, {
   name: 'CompileBlock'
 });
@@ -237,7 +242,8 @@ OPCODE_METADATA(Op.InvokeStatic, {
 
 OPCODE_METADATA(Op.InvokeYield, clearsArgs({
   name: 'InvokeYield',
-  argsPosition: 2
+  argsPosition: 3,
+  netPops: 1
 }));
 
 OPCODE_METADATA(Op.Jump, {
@@ -584,7 +590,7 @@ OPCODE_METADATA(Op.SetBlock, {
   name: 'SetBlock',
   ops: [ScopeSymbol('symbol')],
   operands: 1,
-  stackChange: -2
+  stackChange: -3
 });
 
 OPCODE_METADATA(Op.GetVariable, {
@@ -604,7 +610,7 @@ OPCODE_METADATA(Op.GetBlock, {
   name: 'GetBlock',
   ops: [ScopeBlock('block')],
   operands: 1,
-  stackChange: 2
+  stackChange: 3
 });
 
 OPCODE_METADATA(Op.HasBlock, {
@@ -617,7 +623,7 @@ OPCODE_METADATA(Op.HasBlock, {
 OPCODE_METADATA(Op.HasBlockParams, {
   name: 'HasBlockParams',
   ops: [ScopeBlock('block')],
-  stackChange: -1
+  stackChange: -2
 });
 
 OPCODE_METADATA(Op.Concat, {
diff --git a/packages/@glimmer/vm/lib/opcodes.ts b/packages/@glimmer/vm/lib/opcodes.ts
index c0c96d73ab..7ebce250fc 100644
--- a/packages/@glimmer/vm/lib/opcodes.ts
+++ b/packages/@glimmer/vm/lib/opcodes.ts
@@ -432,6 +432,16 @@ export const enum Op {
    */
   CompileBlock,
 
+  /**
+   * Operation: Push a scope onto the stack.
+   * Format:
+   *   (PushBlockScope #Scope)
+   * Operand Stack:
+   *   ..., →
+   *   ..., Scope
+   */
+  PushBlockScope,
+
   /**
    * Operation: Push a symbol table onto the stack.
    * Format: