Like other major school districts throughout the country, the New York City Department of Education (NYC DOE) has shifted its focus over the last decade from holding high schools accountable for graduation rates to holding them accountable for rates of college and career readiness. There are two major challenges facing both research and policy related to accountability for postsecondary outcomes, however. First, we know relatively little about the conditions under which students are successful in getting college and career ready. Second, we do not yet know in the New York City context to what extent school-level differences in college-going rates are the function of compositional differences--that is, differences in the students' backgrounds and experiences prior to high school--or the function of real differences in school policy and practice. Using an extensive longitudinal database from The New York City Partnership for College Readiness and Success, we employ a variance-partitioning approach to take up these questions. We find, similar to much of the previous literature on school effects, that the bulk of the variation in rates of four-year enrollment is within, rather than between schools, and that compositional effects account for much of the between-school variation. Yet we also find two markers of college-going academic culture that do significantly contribute to the remaining between-school variation: high teacher expectations and access to a college preparatory curriculum. This study also introduces two additional school-level control variables that have not been employed in the national literature on school effects--size and selectivity--and discusses their potential usefulness to the field.