diff --git a/flit/__init__.py b/flit/__init__.py
index c3535a1d..e4554ff3 100644
--- a/flit/__init__.py
+++ b/flit/__init__.py
@@ -60,7 +60,12 @@ def main(argv=None):
     )
     add_shared_install_options(parser_install)
     parser_install.add_argument('--deps', choices=['all', 'production', 'develop', 'none'], default='all',
-        help="Which set of dependencies to install")
+        help="Which set of dependencies to install. If --deps=develop, the extras dev, doc, and test are installed"
+    )
+    parser_install.add_argument('--extras', default=(), type=lambda l: l.split(',') if l else (),
+        help="Install the dependencies of these (comma separated) extras additionally to the ones implied by --deps. "
+             "--extras=all can be useful in combination with --deps=production, --deps=none precludes using --extras"
+    )
 
     parser_installfrom = subparsers.add_parser('installfrom',
        help="Download and install a package using flit from source"
@@ -107,7 +112,8 @@ def main(argv=None):
         from .install import Installer
         try:
             Installer(args.ini_file, user=args.user, python=args.python,
-                      symlink=args.symlink, deps=args.deps, pth=args.pth_file).install()
+                      symlink=args.symlink, deps=args.deps, extras=args.extras,
+                      pth=args.pth_file).install()
         except (common.NoDocstringError, common.NoVersionError) as e:
             sys.exit(e.args[0])
     elif args.subcmd == 'installfrom':
diff --git a/flit/install.py b/flit/install.py
index 8d14f695..2c9cdd26 100644
--- a/flit/install.py
+++ b/flit/install.py
@@ -84,17 +84,24 @@ def __str__(self):
         return ("Installing packages as root is not recommended. "
             "To allow this, set FLIT_ROOT_INSTALL=1 and try again.")
 
+class DependencyError(Exception):
+    def __str__(self):
+        return 'To install dependencies for extras, you cannot set deps=none.'
+
 class Installer(object):
     def __init__(self, ini_path, user=None, python=sys.executable,
-                 symlink=False, deps='all', pth=False):
+                 symlink=False, deps='all', extras=(), pth=False):
         self.ini_path = ini_path
         self.python = python
         self.symlink = symlink
         self.pth = pth
         self.deps = deps
+        self.extras = extras
         if deps != 'none' and os.environ.get('FLIT_NO_NETWORK', ''):
             self.deps = 'none'
             log.warning('Not installing dependencies, because FLIT_NO_NETWORK is set')
+        if deps == 'none' and extras:
+            raise DependencyError()
 
         self.ini_info = inifile.read_pkg_ini(ini_path)
         self.module = common.Module(self.ini_info['module'], ini_path.parent)
@@ -196,10 +203,15 @@ def install_requirements(self):
             return
         if self.deps in ('all', 'production'):
             requirements.extend(self.ini_info['metadata'].get('requires_dist', []))
-        if self.deps in ('all', 'develop'):
-            extra_reqs = self.ini_info['metadata'].get('extras_require', {})
-            for extra in ['dev', 'doc', 'test']:
-                requirements.extend(extra_reqs.get(extra, []))
+
+        extra_reqs = self.ini_info['metadata'].get('extras_require', {})
+        extras_to_install = set(self.extras)
+        if self.deps == 'all':
+            extras_to_install |= set(extra_reqs.keys())
+        elif self.deps == 'dev':
+            extras_to_install |= {'dev', 'doc', 'test'}
+        for extra in extras_to_install:
+            requirements.extend(extra_reqs.get(extra, []))
 
         # there aren't any requirements, so return
         if len(requirements) == 0: