Person–environment (P–E) fit is a central concept in organizational behavior research. Historically, reviews of P–E fit research have summarized empirical studies but said little about whether P–E fit research has made theoretical progress. This chapter applies criteria for evaluating theory to review and assess the theoretical status and progress of P–E fit research. The review encompasses P–E fit theories that span nearly a century and cover research on job satisfaction, job stress, vocational choice, recruitment and selection, and organizational climate and culture. This review indicates that most theories in P–E fit research fall well short of criteria for developing strong theory, and theories presented in recent years are no stronger than those developed decades earlier. Reasons for theoretical stagnation in P–E fit research are identified, and ways to promote theoretical progress are discussed.