>Hello...
>
> I am trying to programmatically highlight a substring of the text that appears within a textbox. For example the first two characters in a string of five aren't highlighted but the next three are. Or four in a string of seven aren't but the last three are...?
>
>Any suggestions..? Thanks In advance :^)

You can use the SelStart and SelLength properties of the textbox to control what gets highlighted.