Urban planning theory has been widely criticised by academics and practitioners as being confused and impractical. In this review paper a tentative first step to remedy the situation is proposed, outlining a new typology of urban planning theories with an aim to clarify the academic discourse and to provide a useful guide for practising planners. Three major ‘debates’ are identified as forming the main streams of thought in the development of urban planning. These are termed the ‘analytical’, ‘urban form’, and ‘procedural’ debates, which are shown to have developed in parallel. The three debates are also shown to focus on different stages of the planning process and to be mainly based on explanatory or prescriptive theories. Hence, it is argued that approaches which have often been described as irreconcilable can constructively coexist under the umbrella of urban planning theories without sacrificing their theoretical underpinnings. In this paper a general evolutionary trend from consensus to diversity is identified across the three streams of thought, and it is shown that, in the future, planning theories are likely to become more explicitly divided between openly politicised approaches and persisting technical-neutral orientations. The structure and evolution of the planning discipline outlined in this paper provide a framework for advancing towards a more clearly defined and coherent body of urban planning knowledge.