Three field studies and one laboratory experiment explore the”mere social information” effect: When donation contributions are affected by information about another’s level of giving. Experiments 1a and 1b demonstrate the effect. Experiment 2 shows it can occur when identity congruence is high. Experiment 3 shows that the effect is a joint function of identity congruence, the strength of identification, and the collective nature of underlying focal thoughts at the time of deciding the amount to give. Theoretical and substantive implications of these findings are discussed.