WEDNESDAY, June 9 (HealthDay News) -- School friends may play a major role in your teen's academic success, a new study suggests.

It included 629 12th graders in Los Angeles who filled out a questionnaire and then kept a record of activities such as time spent studying and time spent with school friends and out-of-school friends.

Students with higher grade-point averages (GPAs) had more school friends than out-of-school friends. The more school friends, the higher the GPA.

"We found that within an adolescent's friendship group, those with a higher proportion of friends who attended the same school received higher grades," Melissa R. Witkow, an assistant professor of psychology at Willamette University, said in a University of California, Los Angeles, news release. "This is partially because in-school friends are more likely to be achievement-oriented and share and support school-related activities, including studying, because they are all in the same environment."

Witkow was a UCLA graduate student when she conducted the study, which was recently published online in the Journal of Research on Adolescence.

The findings don't mean that friends from outside of school aren't beneficial.

"These friendships are still important in terms of fulfilling adolescents' social needs, and they are not necessarily always detrimental to achievement," Witkow said. "For instance, friendships that form in academic settings outside of school, such as at an enrichment class, may very well promote achievement."

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