Newcomers who enter a new group usually possess a number of established social identities. It has been demonstrated that incompatibility between established and new identities decreases social identification with the new group and well-being. We propose that internal motivation to become a group member helps newcomers to identify with their group despite incompatibility. Therefore, it was predicted that only newcomers low (but not high) in internal motivation to become a group member were affected by incompatibility. One experiment with university newcomers and two field studies with exchange students and university newcomers supported these predictions. The results highlight the fact that internal motivation is a strong resource when newcomers face obstacles, in the form of incompatibility between established and new identities.