diff --git a/packages/gatsby/src/schema/index.js b/packages/gatsby/src/schema/index.js
index 444f97352ff8e..922218dd9cc6f 100644
--- a/packages/gatsby/src/schema/index.js
+++ b/packages/gatsby/src/schema/index.js
@@ -2,13 +2,32 @@
 const _ = require(`lodash`)
 const { GraphQLSchema, GraphQLObjectType } = require(`graphql`)
 
+const apiRunner = require(`../utils/api-runner-node`)
 const buildNodeTypes = require(`./build-node-types`)
 const buildNodeConnections = require(`./build-node-connections`)
-const { store } = require(`../redux`)
+const { store, getNodes } = require(`../redux`)
 const invariant = require(`invariant`)
 
+async function getEnhancedGqlFields(typesGQL) {
+  const enhancedFields = await apiRunner(`enhanceSchema`, {
+    types: typesGQL,
+    allNodes: getNodes(),
+    traceId: `initial-enhanceSchema`,
+  })
+  return enhancedFields
+}
+
 module.exports = async () => {
   const typesGQL = await buildNodeTypes()
+  let enhancedFields = {}
+  const enhancedFieldResults = await getEnhancedGqlFields(typesGQL)
+  Object.keys(enhancedFieldResults).forEach(key => {
+    enhancedFields = {
+      ...enhancedFields,
+      ...enhancedFieldResults[key],
+    }
+  })
+
   const connections = buildNodeConnections(_.values(typesGQL))
 
   // Pull off just the graphql node from each type object.
@@ -20,7 +39,7 @@ module.exports = async () => {
   const schema = new GraphQLSchema({
     query: new GraphQLObjectType({
       name: `RootQueryType`,
-      fields: { ...connections, ...nodes },
+      fields: { ...connections, ...nodes, ...enhancedFields },
     }),
   })
 
diff --git a/packages/gatsby/src/utils/api-node-docs.js b/packages/gatsby/src/utils/api-node-docs.js
index 534e55fd055d4..81836970f7de1 100644
--- a/packages/gatsby/src/utils/api-node-docs.js
+++ b/packages/gatsby/src/utils/api-node-docs.js
@@ -203,3 +203,9 @@ exports.onPostBuild = true
  * See gatsby-transformer-remark and gatsby-source-contentful for examples.
  */
 exports.onPreExtractQueries = true
+
+/**
+ * Run after the schema has been created but before it's dispatched allowing you
+ * to do cool enhancements e.g. union / interface stuff
+ */
+exports.enhanceSchema = true