To the extent that a scientific revolution represents a fundamental change in a discipline, the cognitive revolution in psychology was not particularly revolutionary. What changed least in this revolution was methodology. The experimental methods used in cognitive psychology are the same as those used in the behaviorism it overthrew. This methodological continuity results from the fact that both behaviorism and cognitive psychology are based on the same paradigm, which is also the basis of experimental psychology: the open-loop causal model of behavioral organization. A truly revolutionary approach to understanding the mind has been largely ignored because it is built on a paradigm that is inconsistent with conventional research methods. This new approach to psychology, called Perceptual Control Theory (PCT), is based on a closed-loop control model of behavioral organization that is tested using control engineering methods that are unfamiliar to most psychologists. This paper introduces the methodological foundations of closed-loop psychology, explains why the closed-loop revolution has not happened yet, and suggests what psychology might look like after the revolution has occurred.