Raising new questions about the effectiveness of school discipline, a report scheduled for release on Tuesday found that 31 percent of Texas students were suspended off campus or expelled at least once during their years in middle and high school — at an average of almost four times apiece.

When also considering less serious infractions punished by in-school suspensions, the rate climbed to nearly 60 percent, according to the study by the Council of State Governments, with one in seven students facing such disciplinary measures at least 11 times.

The study linked these disciplinary actions to lower rates of graduation and higher rates of later criminal activity and found that minority students were more likely than whites to face the more severe punishments.

"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 1 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.

The findings are "very much representative of the nation as a whole," said Russ Skiba, a professor of school psychology at Indiana University who reviewed the study along with several other prominent researchers.

Several teachers and administrators in Texas were shocked to learn of the report.

"That’s astronomical," said Joe Erhardt, a science teacher at Kingwood Park High School in the Houston suburb of Humble, Texas "I’m at a loss."

Doug Otto, superintendent of the Plano Independent School District, said the data showed that "suspensions are a little too easy."

"Once they become automatic, we’ve really hurt that child’s chances to receive a high school diploma," he added "We’ve got to find ways to keep those kids in school. Don’t get me wrong — we have to provide safe environments for all the other kids. But you have to balance it out and cut down the suspensions and expulsions."

Almost 15 percent of students, a vast majority of whom had extensive school disciplinary files, had at least one record in the juvenile justice system, according to the report.

Minority students facing discipline for the first time tended to be given the harsher, out-of-school suspension, rather than in-school suspension, more often than white students, the study said. (The nature of the offenses was not noted.) A disproportionate number of minority students also ended up in alternative classrooms, where some have complained that teachers are often less qualified.

"What we really need to do is go in to those districts and see if these really are choices being made," Skiba said. "We don’t really know enough about the reasons for African-American and Latino over-representation in school discipline. We have enough data to show that it’s more than just poverty and any greater misbehavior. My guess is it’s very subtle interactional effects between some teachers and students."

Thompson, of the Council of State Governments, said one of the study’s most important findings was how demographically similar schools disciplined students differently. Although Texas law requires suspension or expulsion for certain offenses, Thompson said that 97 percent of suspensions were discretionary, and that suspension rates might say as much about administrators’ discipline philosophy as about student behavior.

"Schools are making very different uses of school discipline," he explained. "And they can have an impact on how often a kid repeats a grade or graduates. We need to recognize that it’s something we need to improve upon."

While the study found links between school discipline and criminal activity, there is no way to know whether one caused the other. Educators have long complained that many students, particularly from poor families, arrive in classrooms with problems far beyond academics that they have few tools to control.

A former alternative-education teacher in Texas, Zeph Capo still remembers the eighth grader who swore at teachers, threw books and pencils, and eventually was suspended and sent into the district’s disciplinary program. Capo said he did not know whether the student straightened out or slipped further. The new study made him only more concerned.

"Are suspensions the tool to improve student behavior and help them be successful? No, I don’t think that’s the case," said Capo, now a vice president of the Houston Federation of Teachers who trains others in classroom management. "Sometimes there’s not a lot of choice left but to risk chaos and anarchy in your school. There are potential times when human beings have had it and they drop the hammer, and maybe the hammer crushes too far."

© 2011 The New York Times Company