The field of Adaptive Control has experienced a rapid growth and change during the last decade with new ideas, concepts, methodologies, theories and applications. New approaches to “robustify” the classical Model Reference Adaptive Control (MRAC) and the Self-Tuning Regulator (STURE) have been developed. A growing number of adaptive architectures employing multiple models have been proposed such as Supervisory Switched Multiple Model Adaptive Control (SMMAC), Unfalsified Control (UC), and Robust Multiple Model Adaptive Control (RMMAC). Some of these architectures will be applicable for adaptive control problems involving nonlinear plants.