Social skill interventions are utilised by educational psychologists (EPs) to promote positive social behaviour amongst pupils. These have predominantly occurred for target populations, rather than at the whole-class level. Research into evidence-based, whole-class interventions for social skill development is warranted. The Good Behaviour Game (GBG) is a contingency management intervention for promoting positive behaviour at the whole-class level. The current study evaluates an adaptation of the GBG to target engagement in social skills in a mainstream primary school classroom setting. An ABAB reversal design was used to evaluate teacher implementation of the GBG. The GBG was shown to be effective in promoting engagement in targeted social behaviour of "positive social interactions" and "working as team". No change in behaviour was observed for the targeted social behaviour of "supporting peers". The paper discusses the implications of the findings, limitations, relevancy to EP practice and impetus for further research.