diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4f002de77e4..0dc47c3557b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,8 @@
 [PR #131](https://github.com/apollostack/apollo-server/pull/131)
 * Improve logging function. Issue #79. ([@nnance](https://github.com/nnance)) in
 [PR #136](https://github.com/apollostack/apollo-server/pull/136)
+* Output stack trace for errors in debug mode. Issue #111. ([@nnance](https://github.com/nnance)) in
+[PR #137](https://github.com/apollostack/apollo-server/pull/137)
 
 ### v0.2.6
 * Expose the OperationStore as part of the public API. ([@nnance](https://github.com/nnance))
diff --git a/package.json b/package.json
index 674c6a269d2..ef01fbe8d8d 100644
--- a/package.json
+++ b/package.json
@@ -61,6 +61,7 @@
     "mocha": "^3.0.0",
     "multer": "^1.1.0",
     "remap-istanbul": "^0.6.4",
+    "sinon": "^1.17.5",
     "supertest": "^2.0.0",
     "supertest-as-promised": "^4.0.0",
     "tslint": "^3.13.0",
diff --git a/src/core/runQuery.test.ts b/src/core/runQuery.test.ts
index 5b57586c8a1..da1620d949f 100644
--- a/src/core/runQuery.test.ts
+++ b/src/core/runQuery.test.ts
@@ -1,6 +1,5 @@
-import {
-  expect,
-} from 'chai';
+import { expect } from 'chai';
+import { stub } from 'sinon';
 
 import {
     GraphQLSchema,
@@ -62,6 +61,12 @@ const QueryType = new GraphQLObjectType({
                 return 'it ' + (<any>Promise).await('works');
             },
         },
+        testError: {
+            type: GraphQLString,
+            resolve() {
+                throw new Error('Secret error message');
+            },
+        },
     },
 });
 
@@ -88,18 +93,46 @@ describe('runQuery', () => {
       });
   });
 
-    it('returns a syntax error if the query string contains one', () => {
-      const query = `query { test`;
-      const expected = /Syntax Error GraphQL/;
-      return runQuery({
-          schema: Schema,
-          query: query,
-          variables: { base: 1 },
-      }).then((res) => {
-          expect(res.data).to.be.undefined;
-          expect(res.errors.length).to.equal(1);
-          return expect(res.errors[0].message).to.match(expected);
-      });
+  it('returns a syntax error if the query string contains one', () => {
+    const query = `query { test `;
+    const expected = /Syntax Error GraphQL/;
+    return runQuery({
+        schema: Schema,
+        query: query,
+        variables: { base: 1 },
+    }).then((res) => {
+        expect(res.data).to.be.undefined;
+        expect(res.errors.length).to.equal(1);
+        return expect(res.errors[0].message).to.match(expected);
+    });
+  });
+
+  it('sends stack trace to error if in an error occurs and debug mode is set', () => {
+    const query = `query { testError }`;
+    const expected = /at resolveOrError/;
+    const logStub = stub(console, 'error');
+    return runQuery({
+        schema: Schema,
+        query: query,
+        debug: true,
+    }).then((res) => {
+        logStub.restore();
+        expect(logStub.callCount).to.equal(1);
+        return expect(logStub.getCall(0).args[0]).to.match(expected);
+    });
+  });
+
+  it('does not send stack trace if in an error occurs and not in debug mode', () => {
+    const query = `query { testError }`;
+    const logStub = stub(console, 'error');
+    return runQuery({
+        schema: Schema,
+        query: query,
+        debug: false,
+    }).then((res) => {
+        logStub.restore();
+        return expect(logStub.callCount).to.equal(0);
+    });
   });
 
   it('returns a validation error if the query string does not pass validation', () => {
diff --git a/src/core/runQuery.ts b/src/core/runQuery.ts
index f16de924a92..ef5314d24c9 100644
--- a/src/core/runQuery.ts
+++ b/src/core/runQuery.ts
@@ -49,6 +49,7 @@ export interface QueryOptions {
 
  formatError?: Function;
  formatResponse?: Function;
+ debug?: boolean;
 }
 
 const resolvedPromise = Promise.resolve();
@@ -62,6 +63,8 @@ function doRunQuery(options: QueryOptions): Promise<GraphQLResult> {
     let documentAST: Document;
 
     const logFunction = options.logFunction || function(){ return null; };
+    const debugDefault = process.env.NODE_ENV !== 'production' && process.env.NODE_ENV !== 'test';
+    const debug = typeof options.debug !== 'undefined' ? options.debug : debugDefault;
 
     logFunction({action: LogAction.request, step: LogStep.start});
 
@@ -73,6 +76,10 @@ function doRunQuery(options: QueryOptions): Promise<GraphQLResult> {
         return errors.map(options.formatError || formatError as any) as Array<Error>;
     }
 
+    function printStackTrace(error: Error) {
+      console.error(error.stack);
+    }
+
     const qry = typeof options.query === 'string' ? options.query : print(options.query);
     logFunction({action: LogAction.request, step: LogStep.status, key: 'query', data: qry});
     logFunction({action: LogAction.request, step: LogStep.status, key: 'variables', data: options.variables});
@@ -123,6 +130,9 @@ function doRunQuery(options: QueryOptions): Promise<GraphQLResult> {
             };
             if (gqlResponse.errors) {
                 response['errors'] = format(gqlResponse.errors);
+                if (debug) {
+                  gqlResponse.errors.map(printStackTrace);
+                }
             }
             if (options.formatResponse) {
                 response = options.formatResponse(response, options);
diff --git a/src/integrations/apolloOptions.ts b/src/integrations/apolloOptions.ts
index 5400a0e27ef..f51643603a2 100644
--- a/src/integrations/apolloOptions.ts
+++ b/src/integrations/apolloOptions.ts
@@ -12,6 +12,7 @@ import { LogFunction } from '../core/runQuery';
  * - (optional) formatParams: a function applied to the parameters of every invocation of runQuery
  * - (optional) validationRules: extra validation rules applied to requests
  * - (optional) formatResponse: a function applied to each graphQL execution result
+ * - (optional) debug: a boolean that will print additional debug logging if execution errors occur
  *
  */
 interface ApolloOptions {
@@ -23,6 +24,7 @@ interface ApolloOptions {
   formatParams?: Function;
   validationRules?: Array<ValidationRule>;
   formatResponse?: Function;
+  debug?: boolean;
 }
 
 export default ApolloOptions;
diff --git a/src/integrations/expressApollo.ts b/src/integrations/expressApollo.ts
index 1cef167ce26..3bbb5a04317 100644
--- a/src/integrations/expressApollo.ts
+++ b/src/integrations/expressApollo.ts
@@ -98,6 +98,7 @@ export function apolloExpress(options: ApolloOptions | ExpressApolloOptionsFunct
           validationRules: optionsObject.validationRules,
           formatError: formatErrorFn,
           formatResponse: optionsObject.formatResponse,
+          debug: optionsObject.debug,
         };
 
         if (optionsObject.formatParams) {
diff --git a/src/integrations/hapiApollo.ts b/src/integrations/hapiApollo.ts
index 9e661dc530e..f822151ff28 100644
--- a/src/integrations/hapiApollo.ts
+++ b/src/integrations/hapiApollo.ts
@@ -141,6 +141,7 @@ async function processQuery(graphqlParams, optionsObject: ApolloOptions, reply)
         validationRules: optionsObject.validationRules,
         formatError: formatErrorFn,
         formatResponse: optionsObject.formatResponse,
+        debug: optionsObject.debug,
       };
 
       if (optionsObject.formatParams) {
diff --git a/src/integrations/integrations.test.ts b/src/integrations/integrations.test.ts
index 33a47b85cc9..863a5627d4f 100644
--- a/src/integrations/integrations.test.ts
+++ b/src/integrations/integrations.test.ts
@@ -1,6 +1,5 @@
-import {
-  expect,
-} from 'chai';
+import { expect } from 'chai';
+import { stub } from 'sinon';
 
 import {
     GraphQLSchema,
@@ -425,6 +424,45 @@ export default (createApp: CreateAppFunc, destroyApp?: DestroyAppFunc) => {
           });
       });
 
+      it('sends stack trace to error if debug mode is set', () => {
+          const expected = /at resolveOrError/;
+          const stackTrace = [];
+          const origError = console.error;
+          console.error = (...args) => stackTrace.push(args);
+          app = createApp({apolloOptions: {
+              schema: Schema,
+              debug: true,
+          }});
+          const req = request(app)
+              .post('/graphql')
+              .send({
+                  query: 'query test{ testError }',
+              });
+          return req.then((res) => {
+            console.error = origError;
+            return expect(stackTrace[0][0]).to.match(expected);
+          });
+      });
+
+      it('sends stack trace to error log if debug mode is set', () => {
+          const logStub = stub(console, 'error');
+          const expected = /at resolveOrError/;
+          app = createApp({apolloOptions: {
+              schema: Schema,
+              debug: true,
+          }});
+          const req = request(app)
+              .post('/graphql')
+              .send({
+                  query: 'query test{ testError }',
+              });
+          return req.then((res) => {
+            logStub.restore();
+            expect(logStub.callCount).to.equal(1);
+            return expect(logStub.getCall(0).args[0]).to.match(expected);
+          });
+      });
+
       it('applies additional validationRules', () => {
           const expected = 'AlwaysInvalidRule was really invalid!';
           const AlwaysInvalidRule = function (context) {
diff --git a/src/integrations/koaApollo.ts b/src/integrations/koaApollo.ts
index d2825413868..386e83c5200 100644
--- a/src/integrations/koaApollo.ts
+++ b/src/integrations/koaApollo.ts
@@ -75,6 +75,7 @@ export function apolloKoa(options: ApolloOptions | KoaApolloOptionsFunction): Ko
           validationRules: optionsObject.validationRules,
           formatError: formatErrorFn,
           formatResponse: optionsObject.formatResponse,
+          debug: optionsObject.debug,
         };
 
         if (optionsObject.formatParams) {
diff --git a/typings.json b/typings.json
index 780cd73f541..6e486b1fb3a 100644
--- a/typings.json
+++ b/typings.json
@@ -2,7 +2,8 @@
   "dependencies": {
     "chai": "registry:npm/chai#3.5.0+20160723033700",
     "graphql": "github:nitintutlani/typed-graphql#ffe7e46e2249cc8f3824a5d15a44938f4354afe9",
-    "http-errors": "registry:npm/http-errors#1.4.0+20160723033700"
+    "http-errors": "registry:npm/http-errors#1.4.0+20160723033700",
+    "sinon": "registry:npm/sinon#1.16.0+20160723033700"
   },
   "globalDependencies": {
     "body-parser": "registry:dt/body-parser#0.0.0+20160619023215",