How do I create a repeater with fixed size that has scrollbars?

Note that the div could also be set in the repeaters HeaderTemplate and FooterTemplate, but then it won't show up at all if the repeater doesn't have ANY data.

Is there a way to get it to just pop up scrollbars for the vertical?

Try overflow:auto; instead of scroll.

Or if you are okay with using the Panels. I have been using it all along.

<asp:Panel ID="pnlContainer" runat="Server" Width="100%" Height="300px" ScrollBars="Auto">
            <asp:Repeater.................................... />
</asp:panel>

Thanks for your help!