A series of experimental studies tests the interactive effects of perceived intergroup dissimilarity and reciprocity expectations on intergroup helping. Hypotheses are derived from a group-level perspective on helping behaviour which suggests that perceived intergroup similarity is a crucial moderator of the psychological processes leading people to help (Stürmer & Snyder, 2010). In Experiment 1 (an online scenario study) intergroup dissimilarity and reciprocity expectations were manipulated as two independent variables. As expected, results revealed a significant similarity by reciprocity interaction. Willingness to help was lowest, when both perceived intergroup similarity as well as expected future reciprocity were low. Expectations of reciprocity, on the other hand, effectively compensated for a lack of perceived intergroup similarity. Internal correlational analyses in the separate experimental conditions further confirmed that the psychological processes leading people to help similar or dissimilar out-groups were of a rather different nature. Specifically, while under conditions of high intergroup similarity helping was driven by feelings of empathy for the out-group (and this even when reciprocity was low); when intergroup similarity was low, helping significantly increased as a function of moral considerations and cost-benefit considerations. Experiment 2 replicated and further extended these results. The theoretical, practical and ethical implications of these findings is discussed.