diff --git a/lib/puppet/provider/group/pw.rb b/lib/puppet/provider/group/pw.rb
index a054d1ff1..b6c74f766 100644
--- a/lib/puppet/provider/group/pw.rb
+++ b/lib/puppet/provider/group/pw.rb
@@ -1,34 +1,48 @@
 require 'puppet/provider/nameservice/pw'
 
 Puppet::Type.type(:group).provide :pw, :parent => Puppet::Provider::NameService::PW do
-  desc "Group management via `pw`.
+  desc "Group management via `pw` on FreeBSD."
 
-  Only works on FreeBSD.
+  commands :pw => "pw"
+  has_features :manages_members
 
-  "
-
-  commands :pw => "/usr/sbin/pw"
   defaultfor :operatingsystem => :freebsd
 
+  options :members, :flag => "-M", :method => :mem
+
   verify :gid, "GID must be an integer" do |value|
     value.is_a? Integer
   end
 
   def addcmd
     cmd = [command(:pw), "groupadd", @resource[:name]]
+
     if gid = @resource.should(:gid)
       unless gid == :absent
         cmd << flag(:gid) << gid
       end
     end
 
-    # Apparently, contrary to the man page, groupadd does
-    # not accept -o.
-    #if @parent[:allowdupe] == :true
-    #    cmd << "-o"
-    #end
+    if members = @resource.should(:members)
+      unless members == :absent
+        if members.is_a?(Array)
+          members = members.join(",")
+        end
+        cmd << "-M" << members
+      end
+    end
+
+    cmd << "-o" if @resource.allowdupe?
 
     cmd
   end
+
+  def modifycmd(param, value)
+    # members may be an array, need a comma separated list
+    if param == :members and value.is_a?(Array)
+      value = value.join(",")
+    end
+    super(param, value)
+  end
 end
 
diff --git a/spec/unit/provider/group/pw_spec.rb b/spec/unit/provider/group/pw_spec.rb
new file mode 100755
index 000000000..3dfc5ec71
--- /dev/null
+++ b/spec/unit/provider/group/pw_spec.rb
@@ -0,0 +1,81 @@
+#!/usr/bin/env rspec
+require 'spec_helper'
+
+provider_class = Puppet::Type.type(:group).provider(:pw)
+
+describe provider_class do
+  let :resource do
+    Puppet::Type.type(:group).new(:name => "testgroup", :provider => :pw)
+  end
+
+  let :provider do
+    resource.provider
+  end
+
+  describe "when creating groups" do
+    let :provider do
+      prov = resource.provider
+      prov.expects(:exists?).returns nil
+      prov
+    end
+
+    it "should run pw with no additional flags when no properties are given" do
+      provider.addcmd.must == [provider_class.command(:pw), "groupadd", "testgroup"]
+      provider.expects(:execute).with([provider_class.command(:pw), "groupadd", "testgroup"])
+      provider.create
+    end
+
+    it "should use -o when allowdupe is enabled" do
+      resource[:allowdupe] = true
+      provider.expects(:execute).with(includes("-o"))
+      provider.create
+    end
+
+    it "should use -g with the correct argument when the gid property is set" do
+      resource[:gid] = 12345
+      provider.expects(:execute).with(all_of(includes("-g"), includes(12345)))
+      provider.create
+    end
+
+    it "should use -M with the correct argument when the members property is set" do
+      resource[:members] = "user1"
+      provider.expects(:execute).with(all_of(includes("-M"), includes("user1")))
+      provider.create
+    end
+
+    it "should use -M with all the given users when the members property is set to an array" do
+      resource[:members] = ["user1", "user2"]
+      provider.expects(:execute).with(all_of(includes("-M"), includes("user1,user2")))
+      provider.create
+    end
+  end
+
+  describe "when deleting groups" do
+    it "should run pw with no additional flags" do
+      provider.expects(:exists?).returns true
+      provider.deletecmd.must == [provider_class.command(:pw), "groupdel", "testgroup"]
+      provider.expects(:execute).with([provider_class.command(:pw), "groupdel", "testgroup"])
+      provider.delete
+    end
+  end
+
+  describe "when modifying groups" do
+    it "should run pw with the correct arguments" do
+      provider.modifycmd("gid", 12345).must == [provider_class.command(:pw), "groupmod", "testgroup", "-g", 12345]
+      provider.expects(:execute).with([provider_class.command(:pw), "groupmod", "testgroup", "-g", 12345])
+      provider.gid = 12345
+    end
+
+    it "should use -M with the correct argument when the members property is changed" do
+      resource[:members] = "user1"
+      provider.expects(:execute).with(all_of(includes("-M"), includes("user2")))
+      provider.members = "user2"
+    end
+
+    it "should use -M with all the given users when the members property is changed with an array" do
+      resource[:members] = ["user1", "user2"]
+      provider.expects(:execute).with(all_of(includes("-M"), includes("user3,user4")))
+      provider.members = ["user3", "user4"]
+    end
+  end
+end