An IEEE Life Fellow, Alberto Isidori is currently a professor of systems and control with Sapienza University of Rome, Italy. Dr. Isidori’s groundbreaking work has changed the way the control systems community thinks about nonlinear control and has helped shape the field. Dr. Isidori’s research in the early 1970s focused on systems realization, resulting in the first complete theory of minimal realization for a class of nonlinear systems. He then extended the geometric theory used for feedback design in multivariable linear systems to general classes of nonlinear systems. This work is considered a milestone in the study of nonlinear feedback systems. Dr. Isidori also developed the concept of nonlinear zero dynamics, which has had fundamental impact on designing feedback laws for nonlinear systems. His contributions to regulation and tracking in nonlinear systems resulted in the design of a feedback law that solves the nonlinear equivalent of the servomechanism problem in linear control. Dr. Isidori’s Nonlinear Control Systems (Springer Verlag, 3rd ed. 1995) is considered the definitive treatment of nonlinear control systems and has had lasting impact.