For years, as standardized tests took on ever greater importance in Massachusetts public schools, recess seemed to pay the price, shrinking or even disappearing in some communities. But now, with an increased focus on kids’ social and emotional development, there is a concerted effort to revive the tradition.

Across the state, a growing number of schools are tapping recess not only to encourage students to be more active but also to teach them a host of skills, such as how to get along with their peers, control their emotions, and take leadership roles.

Many school systems, from Brookline to Medway, are expanding recess or are exploring the idea in response to growing concerns about increased anxiety, stress, and depression among students, while the Legislature is pondering a bill that would require 20-minute recesses at all elementary schools.

The movement is a breath of fresh air to legions of educators and parents who have criticized school systems for whittling away recess to make more time for instruction as part of efforts to boost MCAS scores or to comply with other state mandates.

In some cases, parents have organized themselves into grass-roots groups to push the schools to expand recess.

“I love it,’’ said Kirk Souza, a father of three and a founding member of Bring Back Recess Medway, which successfully lobbied for 10 extra minutes of recess earlier last year at the elementary schools and is now pushing for a formal recess at middle school.

“The thing about recess is that it helps kids physically, emotionally, socially, and academically,’’ he said. “It’s a win-win for kids.’’

Boston has emerged as a leader in this area: This year, it set a new requirement for schools to hold at least 20 minutes of daily recess for students in grades K-8.

And at the Eliot K-8 Innovation School in the North End, there are now 28 minutes alloted to recess.

“What better place to learn social-emotional skills than on a playground,’’ said Jon Gay, executive director of Playworks, a nonprofit that helps oversee the Eliot’s recesses, as he observed dozens of Eliot students skipping rope, shooting hoops, and playing tag at DeFilippo Playground one recent afternoon.

“If kids build self-confidence through play, they will bring it back into the classroom,’’ he said.

As the students played, Eliot principal Traci Walker Griffith called a timeout during a soccer game. A fourth-grader had fallen and, as bad timing would have it, got hit in the head with the ball, knocking off his glasses.

The moment might have prompted laughter from his classmates but instead they respectfully stopped playing and cheered him on as he got back on his feet. For Griffith, the moment revealed a lesson learned during recess: respect.

Research has been building the case to preserve or increase recess time as a powerful tool in developing the physical, mental, and academic well-being of students.

A 2009 study, for instance, found that offering at least one recess period a day for 15 minutes or longer can reduce discipline problems in the classroom. The study, which was published in Pediatrics, the official journal of the American Academy of Pediatrics, examined about 11,000 8- and 9-year-olds nationwide and surveyed their teachers about classroom behavior.

One critical finding revealed an alarming socio-economic divide: Students without recess tended to be black and from households with low incomes and low levels of education in urban areas, where schools have been under pressure to increase academic performance.

Ryan Sherman, director of wellness for Medway schools, said a strong selling point to him was a 2011 study in Preventative Medicine that showed in the vast majority of cases, offering recess caused academic performance to increase or had no effect on it. Rarely did recess have a negative effect on academics.

The resurgence in recess is a sharp departure from two decades ago, when the cherished pastime came under siege — and it wasn’t because of standardized testing.

In 1995 — three years before the state tests premiered — the state began mandating a minimum of 900 instructional hours a year in elementary schools, prompting some officials to shorten lunch and recess in order to comply.

Pressure to maximize instructional time — and the temptation to chisel away at recess —intensified a few years later with the MCAS and then the federal No Child Left Behind Act, which expanded annual standardized testing to grades 3 to 8 in an effort to hold schools more accountable for performance.

The shortening of recess led to heated clashes between parents and school officials, most notably in Peabody, where recess was cut in 2004 from 20 minutes to just 10. The issue turned so volatile that some residents considered adding a provision to the city’s charter to allow recall elections.

On Beacon Hill, the recess bill would offer school systems some relief in scheduling recess: It includes a provision that would allow schools to count recess as instructional time, because it provides an opportunity for students to develop social-emotional skills. That provision is raising concerns with Acting Education Commissioner Jeff Wulfson and others at the state education department.

“Our learning time requirements for elementary schools average about five hours, which should leave time for at least 20 minutes of recess,’’ Jacqueline Reis, a state education spokeswoman, said in a statement. “We want schools to continue to provide at least the minimum amount of learning time that students are entitled to receive without counting recess toward that minimum.’’

Even the Massachusetts Association of School Superintendents, which has been pushing more teaching of social-emotional skills, questions whether the recess bill is necessary.

“I hear from superintendents all the time ‘Why do we have to mandate everything we do?’ ’’ said Tom Scott, the association’s executive director, who estimates that most elementary schools probably already offer 15 or 20 minutes of recess.

When Griffith took over as principal of the Eliot a decade ago, she made recess a central part of her effort to turn around the school, which was struggling with low MCAS scores. Students in the upper grades had 25 minutes for lunch and no recess. She increased the break to 40 minutes to allow for enough time to eat and get outside.

“We want healthy active kids,’’ she said. “Their bodies are growing, and they need movement.’’

Griffith said that even if you take a little time away from instruction to have kids move around, student achievement will actually increase, because students will return to their lessons refreshed and ready to learn instead of just trudging through the rest of the day.

A couple of years ago the school increased the ante further, by emphasizing developing social-emotional skills during recess.

The Eliot through the years saw its state standardized test scores rise, elevating the school to the highest rating in the state’s accountability system. Griffith said she believes recess as well as gym, music, and other enrichment opportunities have been key ingredients in the school’s success.

Hannah Collins, 12, a sixth-grader, said recess is an important part of the school day.

“You need time to release energy,’’ Hannah said. “If we don’t exercise, we won’t be good learners.’’

James Vaznis can be reached at james.vaznis@globe.com.