Stigmatized versus non-stigmatized people advocating on behalf of the stigmatized group are perceived as more biased, suggesting that they might be less effective advocates. Yet, research testing whether stigmatized or non-stigmatized advocates are more persuasive has yielded mixed results. The current work builds on previous research to clarify that this occurs because stigmatized advocates are also perceived as more expert on social justice issues. Six studies document these trade-offs in perceptions. Three studies demonstrate that stigmatized and non-stigmatized advocates seem not to differ in their effectiveness because while perceived expertise boosts the effectiveness of stigmatized advocates, perceived bias undermines it. This occurs both when people confront societal inequality and interpersonal prejudice. Despite the lack of difference in persuasiveness, people predict that the stigmatized advocate will be more effective, suggesting that observers may not recognize perceived bias's role in undermining effectiveness. The present findings differ not only from participants' lay theories, but also from conclusions commonly reached by reviews of the literature which suggest that stigmatized advocates may be less effective than their non-stigmatized counterparts. By examining a broader range of perceptions and effects on audience members' attitudes and intentions to behave consistently with advocacy, we provide a more complete view of these effects.