Enrollment in bilingual education has declined significantly in New York City in recent years, in spite of state and city policies that support it. To better understand this alarming trend, we interviewed school leaders, particularly principals, who have dismantled their school's bilingual education programs in recent years. We also interviewed school leaders who have managed to preserve their bilingual education programs within the same time period. We examined these leaders' knowledge and understandings about bilingual education and their emergent bilingual students, and their rationale for the respective language education policies they have adopted. Our research points to the very important role of school leaders, particularly principals, in sustaining or eliminating bilingual education. We found that the leaders of what we term "English-only" schools had received no formal pre-service preparation to work with emergent bilinguals, while the leaders of "bilingual" schools in our sample were well prepared. We conclude with a call for greater preparation of all school leaders in New York, including principals, by changing their state certification requirements in order to improve the education of emergent bilinguals through the preservation and expansion of bilingual education.