This chapter presents empirical evidence from the application of a behavioural research perspective to shed light on how collective practices of petty corruption are experienced, understood and ultimately justified from the perspective of those directly engaging in them. It explains the relevance of behavioural elements of sociality, in particular through the role of informal social networks prevailing among service users and providers, and places these dynamics in the broader context of anti-corruption frameworks. The chapter shows the manner in which unwritten norms and values upheld by the social networks are associated with corrupt practices in the health services in Tanzania, Uganda and Rwanda. It discusses the implications of the research findings, namely that social rules and expectations constitute a normative framework that coexists with the legal one. The chapter also presents key insights from the case of Rwanda on closing this normative gap. It concludes with the relevance of behavioural factors for understanding petty corruption outcomes and discusses policy recommendations.