Unobtrusive client side validation is one of the great feature that I like in ASP.NET MVC 3. Unobtrusive client side validation feature uses the famous jQuery validation plug-in internally. Jquery validation plug-in perform client side validation lazily. What does this means? This simply means that before submitting the form for the first time, the user can tab through fields without getting any error message. This makes sense and lot of developers and designers like this behavior. But guys coming from places where validation is performed when fields focus out, may not like this behavior. In this article, I will show you how to perform validation on fields when fields focus out.