This book introduces the reader to the concept of functional synchronization and how it operates on very different levels in psychological and social systems – from the emergence of thought to the formation of social relations and the structure of societies. For years, psychologists have investigated phenomena such as self-concept, social judgment, social relations, group dynamics, and cooperation and conflict, but have discussed these phenomena seoarately.This book shows how synchronization provides a foundational approach to these otherwise distinct and diverse psychological processes.This work shows that there is a basic tendency with many processes to become coordinated and progressively integrated into increasingly larger units through well-defined processes. For these larger units, new and largely adaptive functions emerge.  Although synchronization affords progressive integration of system elements to enable correspondingly higher-order functions, the trajectory of synchronization is often characterized by periods of assembly and disassembly of system elements. This occurs when a task is completed and synchronization is no longer essential so that the elements once again operate in an independent fashion. It is argued that the disassembly-resynchronization scenario occurs at all levels of psychological and social reality. The implications of this approach for important issues in interpersonal relations and societal processes are discussed.