The Education Department's civil rights arm says black children represent about 18 percent of children enrolled in preschool programs in schools, but they're almost half of the students suspended more than once.
Six percent of the nation's districts with preschools report suspending at least one preschool child.
Advocates have long said that get-tough suspension and arrest policies in schools have contributed to a "school-to-prison" pipeline that snags minority students, but much of the emphasis has been on middle school and high school policies.
Overall, black students of all ages are suspended and expelled at a rate that's three times higher than that of white children. Black boys receive more than two-thirds of suspensions, and black girls are suspended at higher rates than girls of any other race or most boys.
The data doesn't explain why the disparities exist or why the students were suspended.