Delta Theory establishes the foundation for a true scientific applied psychology, a theory of how human influence induces change in others. Delta Theory is unified and universal, applying to all cultures, historical periods, and goals for change. It integrates concepts and research from psychology, sociology, anthropology, evolution theory, philosophy, psychoneurology, cognitive science, and cultural-historical-activity theory. Yet Delta Theory is clear, economical, and elegant, with a full exposition of tactics for its practices. Rich examples are drawn from professional practices, but also...