Occupational therapy theory, practice and research has increasingly emphasized the transactional relationship between person, environment and occupation. Occupational performance results from the dynamic relationship between people, their occupations and roles, and the environments in which they live, work and play. There have, however, been few models of practice in the occupational therapy literature which discuss the theoretical and clinical applications of person-environment interaction. This paper proposes a Person-Environment-Occupation Model of occupational performance which builds on concepts from the Occupational Therapy Guidelines for Client Centered Practice and from environment-behaviour theories. The model describes interactions between person, occupation and environment, outlines major concepts and assumptions, and is applied to a practice situation.