Entering a new group provides the potential of forming a new social identity. Starting from self-regulation models, we propose that goals (e.g., internal motivation to enter the group), strategies (e.g., approach and avoidance strategies), and events (e.g., the group’s response) affect the development of the social self. In two studies we manipulated the group’s response (acceptance vs. rejection) and assessed internal motivation as well as approach and avoidance strategies. It was expected, and we found, that when newcomers are accepted, their use of approach strategies (but not avoidance strategies) facilitates social identification. In line with self-completion theory, for highly internally motivated individuals approach strategies facilitated social identification even upon rejection. The results underline the active role of newcomers in their social identity development.