Social control is the generic term used to refer to reactions to counter-normative behaviors and to informal social sanctions that can be attributed to deviant individuals. This review of theories and experimental findings addresses the determinants of social control reactions. First, we examine researches in experimental social psychology that show how people's reactions can be inhibited by the presence of others; a phenomenon known as the ‘Bystander effect’. Next, we examine the extent to which group membership factors affect social control. According to the ‘Black Sheep effect’, people are more severe with a deviant when they share their social identity than when he is a member of an out-group. Even though these processes appear as good predictors for social control reactions, other findings highlight that social control and the previous processes could be associated to self-related motivations that are encouraging people to defend themselves through the protection of their group's norms.