This book provides a unified collection of important, recent results for the design of robust controllers for uncertain systems. Most of the results presented are based on H¿ control theory, or its stochastic counterpart, risk sensitive control theory. Central to the philosophy of the book is the notion of an uncertain system. Uncertain systems are considered using several different uncertainty modeling schemes. These include norm bounded uncertainty, integral quadratic constraint (IQC) uncertainty and a number of stochastic uncertainty descriptions. In particular, the authors examine stochastic uncertain systems in which the uncertainty is outlined by a stochastic version of the IQC uncertainty description. For each class of uncertain systems covered in the book, corresponding robust control problems are defined and solutions discussed.