“In the last 20 to 25 years, there have been dramatic increases in the number of suspensions and expulsions,” said Michael Thompson, who headed the study as director of the Justice Center at the Council of State Governments, a nonpartisan group. “This quantifies how you’re in the minority if you have not been removed from the classroom at least once. This is not just being sent to the principal’s office, and it’s not after-school detention or weekend detention or extra homework. This is in the student’s record.”

The study, which followed every incoming Texas seventh grader over three years through high school and sometimes beyond, joins a growing body of literature looking at how to balance classroom order with individual student need.

Several experts said in interviews that the data, covering nearly one million students and mapping each of their school records against any entry in the juvenile justice system, was the most comprehensive on the topic yet. The report did not identify individual districts or schools.