Although school segregation in New York City (NYC) has received a great deal of attention for several decades, the vast majority of contemporary analyses, in the city and elsewhere, exclude private school students. This is mostly due to the fact that formal desegregation efforts have focused on public schools. Yet NYC's enormous private school sector--were it a school district, it would be among the 20 largest in the nation--differs substantially from the city's public sector in terms of the racial and ethnic composition of its students. This report presents findings from a descriptive analysis of segregation by race and ethnicity in all NYC schools in the 2017-18 school year, with a particular focus on comparing the public and private sectors. A summary of the findings is as follows: (1) Racial and ethnic segregation is generally high in both sectors, but it is consistently higher in the private sector; (2) The potential for total citywide integration is constrained by the separation of students between sectors; (3) Schools' religious affiliations play a role in segregation within the private school sector; and (4) Finally, the separation of minority groups "from each other" is an important contributor to school segregation in NYC.