Many individuals feel socially isolated and distressed in ethnically diverse settings. Purpose in life may buffer this form of distress by fostering one’s sense of having a meaningful direction, which may also be of significance to others. In two experience-sampling studies with ethnically diverse participants, we examined associations between the ethnic composition of urban trains and passenger distress, and tested purpose as a moderator of these relationships. Study 1 showed that participants of all ethnic backgrounds reported greater negative mood when the percentage of ethnic out-group members aboard their train increased. However, individual differences in purpose significantly attenuated this effect. Study 2 replicated and extended these findings experimentally by showing that relative to a control condition, briefly writing about purpose prior to boarding trains also diminished the impact of ethnic composition on negative mood. The discussion addresses strategies for promoting positive adjustment in our increasingly diverse society.