Abstract: As an applied field, urban and rural planning derives its knowledge base from the core tasks of planning practice. Land-use regulation therefore constitutes the discipline's conceptual and practical core. By clarifying the meaning of land-use regulation, this paper identifies five principal components of the relevant knowledge base: the characteristics and requirements of different land uses; the organization of land uses; the institutional foundations of public regulation; regulatory methods and processes; and the evaluation of regulatory effectiveness. The research domains extending from this core constitute the knowledge domains of urban and rural planning. At the broadest level, they comprise urban and regional studies, planning theory and history, plan-making, and plan implementation; each can be further divided according to its objects and subject matter. Through comparison with other disciplines, especially foundational disciplines, the paper also identifies the distinctive qualities of planning and its knowledge system.