New research suggests that making community service a requirement for high school graduation may reduce volunteering among older students, Education Week reports.

According to the study, which was published in the Economics of Education Review, Maryland's statewide requirement that students complete seventy-five hours of service learning before graduation led to significant increases in volunteering among eighth-grade students — generally in school-organized activities — but reduced volunteering rates among older students, raising the possibility of lower volunteering rates over the long term. Based on data from a nationally representative survey of eighth-, tenth-, and twelfth-graders, the report found that before the requirement was implemented in 1993, the percentage of high school seniors in Maryland engaged in service activities was 7.8 percentage points higher than the national average. By contrast, between 1997 and 2011, after the service requirement went into effect, the percentage was 9.2 points to 17.4 points lower than the national average, which rose over the same period.

"If this is for school, how do we know [students] are considering this as community service, rather than just homework for school?" said Sara E. Helms, the author of the study and an assistant professor of economics at Samford University. "One of the interpretations that is more convincing is, maybe we are substituting this [requirement] for being self-motivated. Does it dilute the signal value of volunteering?"

Helm's findings may undermine arguments made by proponents of service learning that students who volunteer more frequently are higher-achieving, more engaged in their communities and schools, and less prone to risky behaviors, Education Week reports. Maryland's policy was touted as a way to help students "develop as citizens" and become lifelong volunteers. Although Maryland is the only state to mandate service learning, similar requirements are becoming more common in large school districts across the country. In 2011, nineteen states allowed districts to award credit toward graduation for volunteering or service learning, while seven states allowed districts to require service for graduation, the Education Commission of the States reports.

R. Scott Pfeifer, executive director of the Maryland Association of Secondary School Principals, cautioned that the study's findings may underrepresent less obvious volunteer activities among older students because students may be better able to recall and report official, school-related volunteer activities that they engaged in during middle school. "There's a ton of volunteering that goes on," said Pfeifer, but "kids are social animals. They may not think of their activity in National Honor Society of bringing food to the old-age home as volunteering."

"I'm pro-service learning," said Helms. "However, I think it matters how we implement it. What you hear over and over in the literature is 'don't require service learning; give incentives.' We get very nervous about requiring people to do something because it's good."