Human punishment is biased by ingroup favoritism: we tend to punish outgroup members more harshly than ingroup members. Such preferential punishment of outgroup members could reflect an influence of group membership specifically on punishment, or may reflect a general tendency to respond to outgroup members’ behavior more harshly, regardless of the type of response used. To investigate this question, we contrasted punishment with the decision to reject a partner, often termed partner choice. In two studies, participants interacted with other players in an incentivized economic game. We assigned participants to groups using a “minimal” groups paradigm (Study 1) or a consequential political position (Study 2). Across both studies, when participants could respond to their partner’s behavior with punishment, they punished outgroup members more harshly than ingroup members, replicating past work. We also extend prior work by showing that this difference principally reflects outgroup derogation rather than ingroup love, through the inclusion of neutral individuals in Study 2. In contrast, when participants could respond by either continuing to interact with their current partner or instead reject them and be paired with a new player, participants’ decisions were almost completely unaffected by group membership. Thus, group membership has a strong influence on how we punish others, but almost no influence on how we make partner choice decisions. These results shed light on the breadth of influence group membership can have, especially on how we respond to transgressions, and provide insight into the unique psychological processes supporting punishment and partner choice decisions.