This chapter brings together social and developmental research on ethnic majority youth reactions to growing diversity. It shows no general trend in youth attitudes towards immigrants in recent decades, suggesting that youth reactions may be determined by the proximal social environments they are embedded in. Therefore, this chapter reviews research on the role of proximal social contexts, in particular parents and peers, in shaping youth attitudes. It then proposes an integrative, ecological perspective that looks at the interrelated effects of parent, peer, and school context. It concludes by discussing the challenges and benefits of such an approach, including how it can facilitate more comprehensive models of prejudice development and guide our attempts to ensure positive relations among youth in a diverse world.