This report examines the academic performance of New York City's Catholic elementary schools compared with the city's public schools. Catholic elementary schools enroll 98,000 children in New York City, approximately 14 percent of public school enrollment. The report uses data from the State of New York's fourth and eighth grade tests in English language arts and mathematics. All public schools administer these exams, and private schools do so on a voluntary basis. Data analysis indicates that Catholic schools in New York City are bringing their students to higher levels of achievement than are public schools, regardless of the number of poor and minority students. The higher achievement of Catholic schools is much more pronounced in grade 8 than in grade 4. In English language arts, there is a 17-point difference between Catholic school and public school eighth graders and a 20 point difference in mathematics. Catholic schools come closer to breaking the link between race, family income, and student achievement than do public schools. Catholic schools are more successful at maintaining a basic level of achievement than are public schools. The performance of poor and minority students in the Catholic schools demonstrates the educability of the city's youngsters. The most significant difference between public and Catholic schools in New York City is evidenced in the percentage of students who fall into the lowest performing category. Despite the performance advantage of Catholic schools, compared with public schools, the pass rate on state tests are not high enough in the Catholic system, with math scores in eighth grade particularly low. (SM)