You can control where the grouping will be handled using the GroupLoadMode property of the GridTableView instance. There are two options:
- Server-side - GridTableView.GroupLoadMode.Server - this is the default behavior. Groups are expanded after postback to the server for example:

<MasterTableView GroupLoadMode="Server">

- Client-side - GridTableView.GroupLoadMode.Client - Groups will be expanded client-side and no postback will be performed.

<MasterTableView GroupLoadMode="Client">

and set the ClientSettings -> AllowGroupExpandCollapse attribute to true:

<ClientSettings AllowGroupExpandCollapse="True">

This example demonstrates Outlook� - style grouping implemented with Telerik RadGrid client-side Expand/Collapse of groups.