This chapter will discuss validation of design methods and introduce a model-based approach to validation that is intended to make the process more objective. First, we describe the challenge of validation as it applies to design methods. Then we describe some of the past efforts to create frameworks and concepts for validation in design. Subsequently, we explore new ideas about validation of design methods and their relationship to decision theory. Finally, we propose a model-based technique and use it to evaluate and compare some robust parameter design methods.