In the United States, Asians appear disproportionately underrepresented in leadership roles, a puzzling phenomenon known as the "Bamboo Ceiling" (Hyun, 2005; Lu et al., 2020). We advance a social network explanation for this phenomenon: ethnic homophily. We theorize that East Asians (e.g., ethnic Chinese)-but not South Asians (e.g., ethnic Indians)-are less likely than other ethnicities to emerge as leaders in multiethnic environments partly because East Asians socialize more with ethnic ingroup members (other East Asians). Analyzing a survey of 54,620 Juris Doctor (JD) students from 124 U.S. law schools, Study 1 revealed that East Asians had the highest ethnic homophily of all ethnicities. Studies 2 and 3 examined friendship networks and leadership emergence in 11 class sections of new Master of Business Administration (MBA) students in a U.S. business school, and found that East Asians were the least likely to be nominated and elected as leaders. Social network analysis revealed that, compared to South Asians, Latinos, and Whites, East Asians exhibited higher ethnic homophily, which mediated their lower leadership emergence. These effects occurred for both East Asian internationals and East Asian Americans, and were robust after accounting for variables such as assertiveness (parallel mediator), network centrality, English proficiency, demographics, and personality. By integrating social network analysis into psychology, we identify ethnic homophily as one reason why the Bamboo Ceiling exists for East Asians but not South Asians. Moreover, by uncovering the negative link between ethnic homophily and leadership emergence, our research suggests that bonding with people from different ethnic backgrounds can facilitate individuals' leadership emergence in multiethnic environments. (PsycInfo Database Record (c) 2022 APA, all rights reserved).