I'm not that familiar with .NET's validation, but CF has had built-in form validation for awhile. CF will create JavaScript for you on the fly to validate your form input. You can also insert regular expressions and use that to validate the form input. On the back end, there is some basic server-side validation. However, there are a number of custom tags that can do validation / assertions. And I suspect that there will be CFC's coming out which doe all sorts of neat stuff with forms. FWIW.