diff --git a/README.md b/README.md
index 4167926..0516be0 100644
--- a/README.md
+++ b/README.md
@@ -81,9 +81,14 @@ This is skipped if the requested file already has an extension.
 
 ##### index
 
-By default send supports "index.html" files, to disable this
-set `false` or to supply a new index pass a string or an array
-in preferred order.
+By default *send* supports "index.html" files. To disable this, set index option
+to `false`, or you can be able to supply a new index passing a string with the
+filename or an array in the preferred order.
+
+Alternatively, you can pass a function that will generate the index. The
+function will receive the filesystem absolute path and will have the
+`SendStream` instance as `this` object. You should call internally to the
+`this.send()` method or try to mimic its behaviour.
 
 ##### lastModified
 
@@ -229,7 +234,7 @@ var app = http.createServer(function onRequest (req, res) {
 }).listen(3000)
 ```
 
-## License 
+## License
 
 [MIT](LICENSE)
 
diff --git a/index.js b/index.js
index 81ec0b3..bf4c170 100644
--- a/index.js
+++ b/index.js
@@ -142,13 +142,20 @@ function SendStream (req, path, options) {
     this._dotfiles = undefined
   }
 
-  this._extensions = opts.extensions !== undefined
-    ? normalizeList(opts.extensions, 'extensions option')
-    : []
+  this._extensions = normalizeList(opts.extensions, 'extensions option')
 
-  this._index = opts.index !== undefined
-    ? normalizeList(opts.index, 'index option')
-    : ['index.html']
+  switch (typeof opts.index) {
+    case 'function':
+      this._index = opts.index
+      break
+
+    case 'undefined':
+      this._index = ['index.html']
+      break
+
+    default:
+      this._index = normalizeList(opts.index, 'index option')
+  }
 
   this._lastModified = opts.lastModified !== undefined
     ? Boolean(opts.lastModified)
@@ -542,11 +549,16 @@ SendStream.prototype.pipe = function pipe (res) {
   }
 
   // index file support
+  if (typeof this._index === 'function') {
+    this._index(path)
+    return res
+  }
   if (this._index.length && this.path[this.path.length - 1] === '/') {
     this.sendIndex(path)
     return res
   }
 
+  // Render a file, or an index as a file
   this.sendFile(path)
   return res
 }
@@ -703,6 +715,11 @@ SendStream.prototype.sendFile = function sendFile (path) {
  * @api private
  */
 SendStream.prototype.sendIndex = function sendIndex (path) {
+  if (listenerCount(this, 'index')) {
+    this.emit('index', path)
+    return
+  }
+
   var i = -1
   var self = this
 
diff --git a/test/send.js b/test/send.js
index da101aa..213530d 100644
--- a/test/send.js
+++ b/test/send.js
@@ -702,9 +702,11 @@ describe('send(file).pipe(res)', function () {
         .pipe(res)
       })
 
+      var filePath = path.join(fixtures, 'pets', 'index.html')
+
       request(app)
       .get('/pets/')
-      .expect(200, fs.readFileSync(path.join(fixtures, 'pets', 'index.html'), 'utf8'), done)
+      .expect(200, fs.readFileSync(filePath, 'utf8'), done)
     })
   })
 
@@ -1115,6 +1117,41 @@ describe('send(file, options)', function () {
       .expect(200, '<p>tobi</p>', done)
     })
 
+    it('should support function', function (done) {
+      function index (path) {
+        var res = this.res
+
+        res.end('<p>tobi</p>')
+      }
+
+      var app = http.createServer(function (req, res) {
+        send(req, req.url, {root: fixtures})
+        .on('index', index)
+        .pipe(res)
+      })
+
+      request(app)
+      .get('/')
+      .expect(200, '<p>tobi</p>', done)
+    })
+
+    it('should support function as option', function (done) {
+      function index (path) {
+        var res = this.res
+
+        res.end('<p>tobi</p>')
+      }
+
+      var app = http.createServer(function (req, res) {
+        send(req, req.url, {root: fixtures, index: index})
+        .pipe(res)
+      })
+
+      request(app)
+      .get('/')
+      .expect(200, '<p>tobi</p>', done)
+    })
+
     it('should support disabling', function (done) {
       request(createServer({root: fixtures, index: false}))
       .get('/pets/')