Turkish-origin migrants on average show lower academic performance than Germans. This achievement gap cannot be fully explained by socio-economic differences between the groups. Negative competence stereotypes about Turkish-origin students predict the causal attributions that German preservice teachers make for migrants’ academic underperformance. Specifically, the more strongly preservice teachers endorse negative competence stereotypes, the more likely they are to attribute academic underperformance of Turkish-origin migrants to the migrants themselves and less to the educational system. Stereotype threat theory posits that the activation of stereotypes in test situations can reduce the performance of members of the negatively stereotyped group. Based on this theory, we propose that negative stereotypes provide a social-psychological explanation for the academic underperformance of Turkish-origin migrants compared to Germans. A series of six experiments conducted within a research project funded by the German Ministry of Education and Research investigated stereotype threat effects for Turkish-origin migrants. Two new moderator variables were identified: implicit theory of intelligence and vertical collectivism. A meta-analysis of the six studies showed a small, non-significant mean effect for stereotype threat main effects, but a significant medium-sized mean effect for moderated stereotype threat effects. Limitations and practical implications of stereotype threat effects in educational settings are discussed.