Recent research suggests that the concept of safety culture, specified as traffic safety culture, may have great potential for improving traffic safety. However, as the safety culture concept has been traditionally applied to an organization and its members, the main aim of this paper is to examine how the concept can be applied to road traffic. This is largely a question of which analytical unit the traffic safety culture concept could be applied to. This paper examines three alternatives: (1) local communities, (2) nations, and (3) peer groups. These alternatives are evaluated against four criteria: (A) Is it well defined? (B) Can it be used to explain traffic safety behaviour? (C) Is it possible to influence? (D) Does it provide new insights into traffic safety problems? This paper concludes that while the local community alternative and national alternative appear too heterogeneous, the peer group alternative provides what seems to be a new and promising basis for targeted traffic safety interventions. The discussion indicates, however, issues that need to be examined in further research.