Researchers examined enrollment and family income data from the past 50 years at Catholic, other religious, and nonsectarian private elementary schools (that is, schools serving grades K-8). The study used data on families' incomes and elementary-school choices from the decennial census, Current Population Survey, U.S. Department of Education longitudinal surveys, and the National Household Education Survey, and combined them with data from the Education Department's Private School Universe Survey and survey data from "Phi Delta Kappan." Results find that private schools, like public schools, are increasingly segregated by income. The share of middle-income students attending private schools has declined by almost half, while the private-school enrollment rate of wealthy children has remained steady. Much of the decline among middle-income students is due to falling enrollment at Catholic schools, which have closed in droves in the past 20 years. Private-school enrollment among affluent students has shifted from religious to nonsectarian schools. Enrollment for white students decreased from 16 percent in 1959 to 11 percent in 2013. Enrollment decreased far more dramatically for Hispanic students, dropping from 13 percent enrolled in private schools to 3 percent. By contrast, the private-school enrollment rate increased among black students, from 3 percent to 5 percent.