diff --git a/README.md b/README.md
index 042dbe2..0082c52 100644
--- a/README.md
+++ b/README.md
@@ -161,6 +161,58 @@ By default the string `_` is used as the variable in the map function.
 }]
 ```
 
+## Fn::Flatten
+
+This function flattens an array a single level. This is useful for flattening out nested `Fn::Map` calls.
+
+```json
+{
+  "Fn::Flatten": {
+    "Fn::Map": [
+      [80, 443], "$", {
+        "Fn::Map": [
+          ["10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16"], {
+            "CirdIp": "_",
+            "FromPort": "$",
+            "ToPort": "$"
+          }
+        ]
+      }
+    ]
+  }
+},
+```
+
+Results in:
+
+```json
+[{
+  "CirdIp": "10.0.0.0/8",
+  "FromPort": "80",
+  "ToPort": "80"
+}, {
+  "CirdIp": "172.16.0.0/12",
+  "FromPort": "80",
+  "ToPort": "80"
+}, {
+  "CirdIp": "192.168.0.0/16",
+  "FromPort": "80",
+  "ToPort": "80"
+}, {
+  "CirdIp": "10.0.0.0/8",
+  "FromPort": "443",
+  "ToPort": "443"
+}, {
+  "CirdIp": "172.16.0.0/12",
+  "FromPort": "443",
+  "ToPort": "443"
+}, {
+  "CirdIp": "192.168.0.0/16",
+  "FromPort": "443",
+  "ToPort": "443"
+}]
+```
+
 ## Examples
 
 See [/examples](https://github.com/monken/cfn-include/tree/master/examples) for templates that call an API Gateway endpoint to collect AMI IDs for all regions.
diff --git a/index.js b/index.js
index 90f1cfa..b0820b8 100644
--- a/index.js
+++ b/index.js
@@ -22,31 +22,31 @@ function recurse(base, scope, object) {
   scope = _.clone(scope);
   if (_.isArray(object)) return Promise.all(object.map(_.bind(recurse, this, base, scope)));
   else if (_.isPlainObject(object)) {
-    return Promise.try(function() {
-      if (object["Fn::Map"]) {
-        var args = object["Fn::Map"],
-          list = args[0],
-          placeholder = args[1],
-          body = args[args.length - 1];
-        if (args.length === 2) placeholder = '_';
-        return Promise.resolve(list.map(function(replace) {
-          scope = _.clone(scope);
-          scope[placeholder] = replace;
-          var replaced = findAndReplace(scope, _.cloneDeep(body));
-          return recurse(base, scope, replaced);
-        }));
-      } else if (object["Fn::Include"]) {
-        return include(base, object["Fn::Include"]).then(function(json) {
-          delete object["Fn::Include"];
-          _.extend(object, json);
-          return object;
-        }).then(_.bind(findAndReplace, this, scope)).then(_.bind(recurse, this, base, scope));
-      } else {
+    if (object["Fn::Map"]) {
+      var args = object["Fn::Map"],
+        list = args[0],
+        placeholder = args[1],
+        body = args[args.length - 1];
+      if (args.length === 2) placeholder = '_';
+      return Promise.all(list.map(function(replace) {
+        scope = _.clone(scope);
+        scope[placeholder] = replace;
+        var replaced = findAndReplace(scope, _.cloneDeep(body));
+        return recurse(base, scope, replaced);
+      }));
+    } else if (object["Fn::Include"]) {
+      return include(base, object["Fn::Include"]).then(function(json) {
+        delete object["Fn::Include"];
+        _.extend(object, json);
         return object;
-      }
-    }).then(function(object) {
-      return Promise.props(_.mapValues(object, _.bind(recurse, this, base, scope)));
-    });
+      }).then(_.bind(findAndReplace, this, scope)).then(_.bind(recurse, this, base, scope));
+    } else if (object["Fn::Flatten"]) {
+      return recurse(base, scope, object["Fn::Flatten"]).then(function(json) {
+        return _.flatten(json);
+      });
+    } else {
+      return Promise.props(_.mapValues(object, _.bind(recurse, this, base, scope)))
+    }
   } else {
     return object;
   }
diff --git a/t/include.js b/t/include.js
index e4dc7c4..415b797 100644
--- a/t/include.js
+++ b/t/include.js
@@ -2,10 +2,10 @@ var include = require('../index'),
   assert = require('assert'),
   fs = require('fs');
 
-var tests = ['map', 'literal', 'location'];
+var tests = ['location', 'literal', 'map', 'flatten'];
 if(process.env['TEST_S3']) tests.push('s3');
 
-//var tests = ['map'];
+//var tests = ['flatten'];
 
 tests.forEach(function(file) {
   var tests = require('./tests/' + file + '.json');
diff --git a/t/tests/flatten.json b/t/tests/flatten.json
new file mode 100644
index 0000000..3ab5fe6
--- /dev/null
+++ b/t/tests/flatten.json
@@ -0,0 +1,178 @@
+{
+  "basics": [{
+    "name": "flatten flat list",
+    "template": {
+      "Fn::Flatten": [1, 2, 3]
+    },
+    "output": [1, 2, 3]
+  }],
+  "flatten nested map": [{
+    "name": "nesting with underscore",
+    "template": {
+      "Fn::Flatten": {
+        "Fn::Map": [
+          [1, 2], {
+            "Fn::Map": [
+              [3, 4], {
+                "foo": "_"
+              }
+            ]
+          }
+        ]
+      }
+    },
+    "output": [{
+      "foo": "3"
+    }, {
+      "foo": "4"
+    }, {
+      "foo": "3"
+    }, {
+      "foo": "4"
+    }]
+
+  }, {
+    "name": "flatten custom placeholder",
+    "template": {
+      "Fn::Flatten": {
+        "Fn::Map": [
+          [1, 2], "$", {
+            "Fn::Map": [
+              [3, 4], {
+                "foo": "_",
+                "bar": "$"
+              }
+            ]
+          }
+        ]
+      }
+    },
+    "output": [{
+      "foo": "3",
+      "bar": "1"
+    }, {
+      "foo": "4",
+      "bar": "1"
+    }, {
+      "foo": "3",
+      "bar": "2"
+    }, {
+      "foo": "4",
+      "bar": "2"
+    }]
+
+  }, {
+    "name": "nesting with underscore and includes",
+    "template": {
+      "Fn::Flatten": {
+        "Fn::Map": [
+          ["includes/foobar.json", "includes/subfolder/include2.json"], {
+            "Fn::Map": [
+              ["includes/foobar.json", "includes/subfolder/include2.json"], {
+                "foo": "bar"
+              }
+            ]
+          }
+        ]
+      }
+    },
+    "output": [{
+      "foo": "bar"
+    }, {
+      "foo": "bar"
+    }, {
+      "foo": "bar"
+    }, {
+      "foo": "bar"
+    }]
+
+  }],
+  "include": [{
+    "name": "include template with variables",
+    "template": {
+      "Fn::Flatten": {
+        "Fn::Map": [
+          [1, 2], "$", {
+            "Fn::Map": [
+              [3, 4], {
+                "Fn::Include": "includes/mapvariable.json"
+              }
+            ]
+          }
+        ]
+      }
+    },
+    "output": [{
+      "foo": "3",
+      "bar": "1",
+      "baz": [{
+        "foo": "3",
+        "bar": "1"
+      }]
+    }, {
+      "foo": "4",
+      "bar": "1",
+      "baz": [{
+        "foo": "4",
+        "bar": "1"
+      }]
+    }, {
+      "foo": "3",
+      "bar": "2",
+      "baz": [{
+        "foo": "3",
+        "bar": "2"
+      }]
+    }, {
+      "foo": "4",
+      "bar": "2",
+      "baz": [{
+        "foo": "4",
+        "bar": "2"
+      }]
+    }]
+  }],
+  "synopsis": [{
+    "name": "flatten nested map",
+    "template": {
+      "Fn::Flatten": {
+        "Fn::Map": [
+          [80, 443], "$", {
+            "Fn::Map": [
+              ["10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16"], {
+                "CirdIp": "_",
+                "FromPort": "$",
+                "ToPort": "$"
+              }
+            ]
+          }
+        ]
+      }
+    },
+    "output": [{
+      "CirdIp": "10.0.0.0/8",
+      "FromPort": "80",
+      "ToPort": "80"
+    }, {
+      "CirdIp": "172.16.0.0/12",
+      "FromPort": "80",
+      "ToPort": "80"
+    }, {
+      "CirdIp": "192.168.0.0/16",
+      "FromPort": "80",
+      "ToPort": "80"
+    }, {
+      "CirdIp": "10.0.0.0/8",
+      "FromPort": "443",
+      "ToPort": "443"
+    }, {
+      "CirdIp": "172.16.0.0/12",
+      "FromPort": "443",
+      "ToPort": "443"
+    }, {
+      "CirdIp": "192.168.0.0/16",
+      "FromPort": "443",
+      "ToPort": "443"
+    }]
+  }]
+}