The District’s charter schools expelled far fewer students in the 2012-13 school year than the school year before, but individual charters’ expulsion rates continued to vary widely, according to D.C. Public Charter School Board data released Tuesday.

Charters’ overall expulsion rate fell 27 percent as the number of students removed for disciplinary reasons dropped from 227 in 2011-12 to 186 in the past school year. By comparison, D.C. Public Schools expelled three students in 2011-12; there was one expulsion in 2012-13.

The decrease in charter expulsions comes amid increased public scrutiny of the schools’ discipline policies. D.C. charters expelled students at a rate more than three times the national average in 2011-12 — the rate was 72 times higher than in the city’s traditional school system — according to a Washington Post analysis earlier this year.

“I think that the charter schools are revisiting their policies to provide safe environments for all students while trying not to exclude students — or when you exclude them, for as short a time as possible,” said Naomi DeVeaux, deputy director of the D.C. Charter Board.

Critics have said that charters, which have the freedom to design their own discipline policies, expel students excessively and with too little oversight. Many charter leaders say that they remove students only when necessary to ensure that their classrooms are safe and conducive to learning.

“Nobody wants to see high expulsion rates, but no one wants to see schools that aren’t safe,” said Susan Schaeffler, chief executive officer of the KIPP DC charter network. “It’s a very difficult balance between the two.”

KIPP DC College Preparatory, a high school, expelled 17 students in 2011-12 — or 5 percent of its enrollment. In 2012-13, the rate plummeted by 85 percent: Three students were removed for disciplinary reasons.

Schaeffler said the decrease stems partly from policy changes meant to prevent discipline problems, including shorter passing periods between classes and a revised demerit system that emphasizes rewards over punishment.

But in future years, expulsion rates could be higher, she said, adding that discipline data normally fluctuate because of student behavior, which varies from year to year for many reasons. One violent incident involving many students can boost expulsion rates quickly, she said, and although KIPP DC watches its discipline data closely, officials will continue to expel students if necessary to maintain safety.

More than half of the city’s 102 charter campuses recorded zero expulsions in the past school year. But not every school saw a decrease. Parkside Middle, a campus of the Cesar Chavez Public Charter Schools for Public Policy, expelled 12 students in 2012-13, four times as many as the year before.

YouthBuild, an alternative high school that caters to students who have dropped out or are older than 16, previously had the highest expulsion rate in the city. It expelled 30 students, or nearly one-third of its population, in 2011-12. That rate dropped 85 percent the next school year, when five students were expelled.

There was also a significant drop at Friendship Collegiate Academy, where 18 students were expelled in 2012-13 — far fewer than the 56 students expelled the year before.

Officials at YouthBuild and Friendship Collegiate did not respond to a request for comment Tuesday.

There was also an increase at Integrated Design Electronics Academy, or IDEA, where last year 13 students, or 4.4 percent of the school, were expelled. It had the second-highest expulsion rate in the city. Students were expelled for infractions including physical assault, marijuana possession, and stealing and using a staff member’s credit card.

“It goes without saying that such conduct is anathema to a learning environment conducive to high quality instruction and student learning,” Justin Rydstrom, principal of IDEA, wrote in an e-mail.

The expulsions came as the school, which was nearly closed because of poor academic performance in 2012, made a concerted effort to turn itself around, restructuring its leadership, bringing in new faculty members, and making double-digit gains on math and reading tests.

IDEA has not expelled any students this fall, Rydstrom said.

The D.C. Public Charter School Board began publishing suspension and expulsion data about two years ago in order to inspire change without additional regulations. The board is to discuss 2012-13 data at its monthly meeting Wednesday.

Expulsions offer only a partial picture of mid-year student mobility. In 2011-12, nearly 2,000 students withdrew from charters mid-year, and 561 of them then enrolled in the traditional school system.

Some students move out of the city or decide on their own to switch schools. But others, according to parents and activists, withdraw after a disciplinary violation in order to avoid being expelled.

Principals in the District’s traditional public school system — who are obligated by law to enroll neighborhood children — say they see a mid-year influx of students who were previously enrolled in charter schools but left because of behavior problems.

DeVeaux, the charter-board official, said the board and the school system are planning to jointly release new “equity reports” in mid-November. For the first time, the reports will publicize mid-year withdrawal rates at each school.