A brief review of criticism in certain areas of planning seems to indicate the need for the adoption of an environmental perception and behaviour approach. The conceptual basis of this approach is established leading to the development of a paradigm of the man‐environment relationship based on perception, which in turn provides the central feature of a model of human spatial decision‐making behaviour. Mental images of the environment are postulated as forming the core determinants or influences of human spatial behaviour. Results of empirical studies using this approach can outline the significant factors in human decisions and views concerning the environment. The value of the approach is that it emphasises the relativity of mental images in all stages of the planning process and that it links planning decision‐making to a more realistic paradigm of man‐environment relationships. Some examples of the application of this approach to specific areas of planning are given.