This textbook is designed for an advanced course in Control Theory. Basic courses in control typically cover linear time invariant systems with one input and one output. Since industrial processes often have several inputs and outputs and contain nonlinearities, these topics need to be covered in a second course. Control Theory explains current developments in multivariable and nonlinear control techniques, and looks at tools for computer aided design, for example Matlab and its toolboxes. It is now possible for practical engineering to use many of the recent developments based on deep mathematical results, such as H-Infinity methods and exact linearization. To make full use of computer design tools, a good understanding of their theoretical basis is necessary, and to enable this the book presents relevant mathematics clearly and simply. The practical limits of control systems are explored, and the relevance of these to control design are discussed. The book is ideal for a final year undergraduate or postgraduate course, and the student is helped by a series of exercises at the end of each chapter. Professional engineers will also welcome Control Theory as a core reference.