Hi I'd like to use System.Windows.Data.IValueConverter, but when I try to add a reference to System.Windows.Data in VS2010, I only see System.Windows.Forms and System.Windows.Presentation. What am I missing? I'm using .NET 3.5 (not the client version), and I think the library should exist for that version. Switching my project to .NET 4.0 didn't help. Googling didn't turn up any people experiencing this problem. TIA.