<p>In ASP.NET (not MVC), what is the best approach to programmatically setting styles on an unordered list used for navigation so the appropriate menu item is styled as the active item if that page is being viewed?  </p>

<p>This would most likely be used in conjunction with a MasterPage.</p>

The answer to your question depends a lot on how you have your list implemented {User control or not, etc}.  How I would do it, is implement the list to be generated by a user control.
I'd have the UserControl tag each element with something like:
```
```
<{...} class="GeneratedMenuItem"> {...}
```
```
And I'd have the appropriate styles in the Style Sheet; of course if it was in a user control then you might be able to use Themes (but that depends on which version of ASP.net you are using.