Within the framework of an intergroup relations paradigm, three studies analysed the role of in-group threat in intergroup discrimination and the influence of in-group norms on intergroup discrimination. The first study showed that perceived socio-economic threat underlies Swiss nationals' prejudice and discrimination toward foreigners in Switzerland. The second and third studies experimentally tested the hypotheses, first, that variations in perception of in-group threat will produce change in initial discrimination, and, second, that the influence of an in-group norm (pro- vs. anti- discriminatory) is moderated by the perception of in-group threat. In support of these predictions, results of both studies indicated that discrimination was reduced when perceived in-group threat was low. However, the anti-discriminatory in-group norm reduced discrimination only when perceived in-group threat was low. No influence was observed for the pro-discriminatory in-group norm. Copyright © 2004 John Wiley & Sons, Ltd.