It is argued that the difficulties inherent in present‐day social psychology stem largely from the fact that insufficient consideration has been given to the psychological properties of social behaviour. An analytic distinction between nomic, idiosyncratic and reconstructive aspects of social behaviour is introduced and used to show that what is typically revealed in experiments is not the operation of psychological processes, i.e. the different ways in which individuals discover, apply and otherwise use the rules regulating everyday social life in pursuing their own purposes. Rather, it is argued that such investigations reveal merely the shared rules regulating behaviour in the situation under investigation, due to the fact that the experimental situation tends to enforce the operation of nomic models, thereby eliciting behaviour which does no more than reflect the sources of regulative influence working in experimental episodes. It is further argued that this emphasis on nomic social behaviour, together with a failure to distinguish between the social and psychological levels of analysis in social behaviour, leads to inferential dilemmas. A method (the thought experiment) is offered as a means of detecting the operation of nomic models. It is contended that once the nomic aspects of social behaviour are identified, it will be possible to study the psychological processes employed in utilizing rules. While the study of nomic aspects of social behaviour is seen as necessary, it is argued that different methodologies need also to be adopted in order to establish a psychologically informative social psychology.