Thanks, I know the shortcut because I'm an old C++ hand. I'm binding to a grid, though, not a textbox. But I found the solution, and you'll be pleased I was able to keep in inline using the same syntax.
I replaced this
<asp:BoundColumn DataField="Active" SortExpression="Active" HeaderText="Active"></asp:BoundColumn>
with this
<asp:TemplateColumn SortExpression="Active" HeaderText="Active">
<ItemTemplate>
<asp:Label runat="server" Text='<%# ((bool)DataBinder.Eval(Container, "DataItem.Active")) ? "Yes" : "No" %>'></asp:Label>
</ItemTemplate>
</asp:TemplateColumn>
(grid is read-only or <EditTemplate> would be necessary too)