New York City public-school students can no longer be suspended for one-time, low-level infractions, and the youngest pupils can be suspended only for 5 days for midlevel offenses, down from 10, according to new disciplinary rules posted by the Education Department this week.

With an aim of reducing punishments that keep students out of the classroom, the department’s new disciplinary code also guides teachers to intervene quickly with misbehaving students and to try counseling before moving to punishment.

“We want to be able to address improper behavior before it reaches a higher level,” said Marge Feinberg, a department spokeswoman. “And to do that, we are focused on providing strong student support services coupled with parent involvement.”

Under the new code, which is reviewed and revised annually, students in all grades will no longer face any form of suspension for transgressions like being late for school, being absent without an excuse, talking back to teachers or school leaders, or carrying prohibited items like smartphones and beepers. They can still be punished in other ways, including being kept from extracurricular activities or being sent to the principal’s office. And students repeatedly removed from the classroom for low-level offenses can still, in limited instances, be suspended.

For those in kindergarten through third grade, the new code reduced the maximum suspension to 5 days from 10 for certain midlevel infractions, like shoving, engaging in minor altercations or drawing graffiti on school property. More serious misbehavior like bullying, violent fights or starting fires can still lead to longer suspensions, as much as 90 days in some cases or a year if a firearm is involved.

In severe cases, a student can be moved to a school that specializes in students with disciplinary problems. The rules on expulsion from the system have not changed. It is possible only for students at least 17 years old, and it happens rarely: two cases in the past three years, according to Ms. Feinberg.

City Council members and advocates including the New York Civil Liberties Union had pushed for changes to the code, arguing that suspensions were too harsh or unnecessary in many cases, needlessly keeping students out of school. A 2010 city law required the Education Department to regularly report data on school suspensions. According to the most recent report, 73,441 suspensions occurred in the 2010-11 year, compared with 71,721 in the previous year — a 2.4 percent increase. It was unclear how many of those cases would not have resulted in suspensions under the new policy.

“The overarching message is that students belong in the classroom,” said Donna Lieberman, executive director of the New York Civil Liberties Union. “This change in the disciplinary code would result in more students in the classroom, more often, and teachers having the mandate to discipline students with positive educational approaches.”

In City Council testimony in June, the civil liberties group said there were 31,879 suspensions in 2002-3, the first year of the Bloomberg administration.

Michael Mulgrew, president of the United Federation of Teachers, the New York City teachers’ union, criticized the administration for instituting new rules that did not adequately address the core reasons underlying students’ misbehavior.

Mr. Mulgrew pointed to one new section of the code — titled “Progressive Ladder of Support and Disciplinary Consequences,” — and criticized it as a set of “buzzwords.”

He said that in order to adhere to the new policies that called for more counseling instead of suspensions, teachers would need more training and more support from professionals like guidance counselors and psychologists.

“Student behavior and school culture is about having the right services in place,” said Mr. Mulgrew, who added that the number of guidance counselors had gone down recently. “This looks like a quick little fix to get the number of suspensions down,” he said.