Schools and friendships represent important but distinct contexts for adolescent identity development. However, research has yet to explore the long-term interplay between these factors on ethnic/racial identity (ERI). This study included a sample of 640 adolescents from 9 public high schools in a diverse United States metropolis (M_age = 14.50, SD = 0.67; 44% Asian, 20% Black, 36% Latinx; female = 68%, male = 32%, non-binary = 0%). Latent growth curve modeling was conducted to investigate longitudinal associations in friendship ethnic/racial composition and ERI exploration. From the 9th–11th grades, same-race friends and ERI exploration increased linearly whereas friendship ethnic/racial diversity decreased linearly. Adolescents attending more ethnically/racially diverse schools maintained more ethnically/racially diverse friends over time but did not differ in changes in ERI exploration compared to adolescents in less diverse schools. There was no association between the rates at which adolescents’ friendship ethnic/racial composition and ERI changed over time. More ethnically/racially diverse friends in the 9th-grade predicted faster increases in subsequent ERI exploration. The findings highlight important differences in the roles of friendship and school contexts on ERI, suggesting that friendship ethnic/racial diversity, but not school ethnic/racial diversity, facilitated ERI exploration over time. School ethnic/racial diversity did facilitate a slower decline in friendship ethnic/racial diversity, emphasizing the importance of school integration.

学校和友谊代表了青少年身份发展的重要但独特的背景。然而，研究尚未探索这些因素对民族/种族认同（ERI）的长期相互作用。这项研究包括来自美国一个多元化大都市 9 所公立高中的 640 名青少年样本（男性_年龄= 14.50，SD = 0.67；44% 亚裔，20% 黑人，36% 拉丁裔；女性 = 68%，男性 = 32% ，非二进制 = 0%）。潜在增长曲线模型旨在研究友谊民族/种族构成和 ERI 探索中的纵向关联。从 9 年级到 11 年级，同种族朋友和 ERI 探索呈线性增加，而友谊的民族/种族多样性呈线性下降。随着时间的推移，就读于种族/种族更加多元化的学校的青少年会保持更多种族/种族多样化的朋友，但与就读于种族较少的学校的青少年相比，ERI 探索的变化没有差异。青少年友谊的民族/种族构成与 ERI 随着时间的推移而变化的比率之间没有关联。九年级的更多种族/种族的朋友预测随后的 ERI 探索会更快增加。研究结果强调了友谊和学校环境对 ERI 的作用的重要差异，表明友谊的民族/种族多样性，而不是学校的民族/种族多样性，随着时间的推移促进了 ERI 探索。学校的民族/种族多样性确实促进了友谊民族/种族多样性的缓慢下降，强调了学校融合的重要性。