Is the better performance of new small schools gained at the expense of losses elsewhere or does small school reform lift the whole district?  In this paper we explore New York City’s small high school reform in which hundreds of new small high schools were built in less than a decade.  We use a rich administrative dataset of individual student level data on four cohorts of NYC high school students, and estimate the effects of schools on student outcomes using an instrumental variables approach.  Our results suggest that the introduction of small schools improved outcomes for students in all types of schools, including large schools, small schools, continuously operating schools, and new schools. Small school reform lifted all boats.