On the third Thursday of each month, several parents appear in the Northfield Elementary School cafeteria in Ellicott City, Maryland. They wear green t-shirts and hand out conversation cards to the students seated at the long, gray lunchroom tables. There’s an air of excitement — today, the kids don’t have to sit with their usual classmates and are instead encouraged to get to know someone new.

The students are taking part in Start With Hello, one of the evidence-based programs designed by the team at Sandy Hook Promise, a nonprofit formed in 2013 by parents who lost children in the 2012 elementary school shooting in Newtown, Connecticut.

The suite of programs, called Know the Signs, is designed to teach youth and adults how to prevent school violence, shootings, and other harmful acts. The goal of Start With Hello is to teach students to be more socially inclusive. “Everything we do has a nexus to 2012,” said co-founder and managing director Mark Barden, who lost his 7-year old son, Daniel, at Sandy Hook. “We know that the killer was chronically, severely socially isolated. Our research shows that people in that situation are at increased risk for violence and self harm.”

Sandy Hook Promise itself has largely avoided more politically fraught issues related to regulations on guns and restricting gun access. Instead, it focuses on mental health and wellness, gun safety, and research, and tries to appeal to a wide spectrum of people on all sides of the gun debate. “We are all about developing compassion and empathy,” said Aimee Thunberg, the group’s communications director. Thunberg says the organization regularly receives correspondence from gun rights advocates, inquiring about the organization’s mission.

Northfield began its Start With Hello efforts in 2016, at the behest of parents Karen Herren and Buffy Beaudoin-Schwartz, who grew up in Newtown. “We brought the idea to the administration, and they immediately embraced it,” said Beaudoin-Schwartz.

The two parents, the school administration, and the school’s Parent Teacher Association began the program with grades three through five. Today, its multipronged approach is familiar to all students and staff. Parents, students, teachers, and administrators have all enthusiastically embraced it.

The Start With Hello program now operates in 11,600 schools across the nation. It’s free to all participants, with costs covered by public and private grants. “Our priority is sustainability, to build it into the schools and clubs to create a culture of inclusivity,” Barden said. “It empowers students to help end social isolation.”

Schools that adopt Start With Hello receive free training in three areas: recognizing the signs of extreme, chronic loneliness; instructing students on what they can do to help others feel included; and encouraging them to break the ice and start a conversation with peers they haven’t regularly interacted with.

At Northfield, administrators used those guidelines to develop the monthly lunches, as well as a “buddy bench,” a social intervention technique designed to foster inclusion on school playgrounds that has been associated with reductions in solitary behavior, according to a 2017 study by the International Electronic Journal of Elementary Education. “Students know that if they see someone sitting on the bench, that person might be feeling lonely or sad, and they are encouraged to join him or her,” said Patty Morse, a mother of three and one of the coordinators of the Northfield program.

Dr. Peter Langman, a psychologist and author of two books on school shootings, believes that the Start With Hello program is an effective part of an overall approach to gun violence prevention. “In a broader sense, anything that can promote a positive peer culture and reduce isolation is good,” he said. “Mass school shootings are still rare, but students dealing with mental health issues are extremely common.”

While school shootings represent a fraction of overall gun violence, their rate has steadily increased since the Columbine High School shooting in 1999, and the phenomena is virtually unheard of in any other country.

“Nothing is simple and clear,” Langman said, “but there’s something to be said for preventative programs that help students get to know each other as people, and not as a clique or a type.”

Access to firearms remains a major contributing factor to school violence, according to numerous studies, including a U.S. Secret Service report published last month on school shootings over a 20-year period. But the report also identified a social component. It found that all shooters in the study “experienced social stressors involving their relationships with peers and/or romantic partners.” Further, the report noted that most attackers had been victimized by bullying and had a history of disciplinary problems. The Centers for Disease Control and Prevention similarly recognizes a multitude of social risk factors for school violence, including rejection by peers.

In 2017, Sandy Hook Promise worked with the University of Michigan and the Los Angeles Unified School District on a case-control study of students who have attended the organization’s programs. The overall study is still ongoing, but a completed portion — which covered 190 respondents — found that those who participated in Start With Hello were more likely to report signs of mental distress and threats, and had more positive relationships with trusted adults, than the students who did not attend the training. “These findings are pretty exciting,” said Justin Heinze, lead researcher and an assistant professor at the University of Michigan. “We’ve found some initial evidence that Start With Hello can have a positive influence on several different outcomes that affect school climate and school safety.”

Morse, one of the coordinators of the Northfield program, says Start With Hello is making a difference. “We’ve had feedback from parents who tell us their kids had a great day because they had company at lunch,” she said. “If we can affect even one child and make him or her feel less isolated, we’ve done our job.”