The influence of ingroup norms (pro-discrimination vs. anti-discrimination) has been examined in a sample of 222 Swiss university students (144 women) as a function of the initial ingroup bias (egalitarian vs. discriminatory participants), the perceived immigrants' ability to adapt themselves in Switzerland (moderate vs. high), and the threat immigrants introduce to the Swiss national identity (low vs. high). Ingroup norm and ingroup threat were experimentally manipulated, whereas initial ingroup bias and perceived immigrants' ability were assessed at the beginning of the study. The main dependent variable was the change in the ingroup bias. Significant effects were observed only among the initially discriminatory participants. The antidiscrimination norm was influential (i.e. decreased ingroup bias) when the threat was low and the immigrants were perceived as highly adaptable in Switzerland. On the other hand, the pro-discrimination norm was influential (i.e. increased ingroup bias) when the threat was high and immigrants were perceived as only moderately adaptable. These findings confirm the importance of factors, both contextual and dispositional, that legitimate the processes of normative influence.