ASP.NET MVC 2 has validation architecture that support both server-side and client-side validation. ScottGu describes in details how to get validation works in his post ASP.NET MVC 2: Model Validation. The best feature in client-side architecture is that you may use alternative java scripts validation libraries like jQuery validation. There is a steps to get client-side validation works using jQuery validation plug-in:

  1. Download and add to your ASP.NET MVC project following java scripts:

    I assume you put all scripts into /Scripts folder of your MVC application

  2. Enable client side validation
    • add three JavaScript references to your view
    • write one line of code in the view before form

That's it! Now you have Client-side validation using jQuery validation plug-in!