We study the role of intergroup mobility in the emergence of conflict. Two groups compete for the right to allocate society's resources. We allow for costly intergroup mobility. The winning group offers an allocation, which the opposition can accept or reject, and wage conflict. Agents can also switch group membership. Expropriating a large share of resources increases political strength by attracting opposition members, but implies a higher threat of conflict. Our main finding is that the possibility of intergroup mobility affects the likelihood of conflict in a nonmonotonic way. Open conflict can arise at intermediate costs of mobility. (JEL D71, D72, D74)