Along with formal knowledge and technology, individual, professional and societal value systems are fundamental determinants of numerous aspects of the built environment. Despite this importance, there appears to be no well-established, coherent and systematic framework for a discussion of value related issues in environmental analysis. This paper addresses the problem by considering the fundamental concepts that may be used in a discussion of values and interrelates them to form a conceptual framework. The preliminary discussion is centered around the need for and the importance and effect of value systems in the activity of designing, constructing and using the built environment. The concepts that form the elements of the framework are based on a process model describing the life-cycle of the built environment. It is claimed that the values held by planners, designers, builders and users have significant effects on this process. Concepts such as value, value judgement and value system are discussed and illustrated in environmental terms through examples. Further discussion concerns the origin and formation of values, their nature and types, codification; the expression and transfer of value judgements, changes in and conflicts between value systems. The paper concludes with suggestions for possible topics of research related to values in the built environment.