Research on the interindividual–intergroup discontinuity effect has demonstrated that intergroup relations are often less cooperative than interindividual relations. The aim of the present paper is to test whether mere social categorization suffices to create a group‐motivated discontinuity effect. In two experiments, we manipulated actors' personal versus social identity salience, whereas controlling for actors' outcome independence (1 : 1) versus interdependence (3 : 3). Making actors' social identity salient using a minimal group treatment was sufficient to increase defection in a Prisoner's Dilemma Game, irrespective of whether this was in an interindividual or intergroup interaction (Experiment 1). Using a Mutual Fate Control matrix in Experiment 2, results indicate that this effect can be attributed to actors' increased motivation to maximize relative differences to outgroup opponents under social identity salience.