Professor Goodwin has made outstanding contributions to the area of systems science and dynamical systems over a period of 25 years. His work has had a major international impact and is known in virtually every country in the world. Of particular significance is his capacity to link fundamental theoretical research with engineering applications. He made pioneering contributions of lasting significance on the convergence of adaptive controllers and on numerical issues in digital filtering and control. More recent work on switching strategies in adaptive control may turn out to be a key concept in the emerging area of hybrid dynamical systems.