There’s been a lot of research to suggest that kids’ friends influence their social development, but less is known about how friends influence academic performance. A new study shows that your kids’ friends may have a big impact on how well they do in school.

The research team looked at certain academic and behavior characteristics of almost 1,300 kids and their friends once when the kids were in 6th grade and again when they were in 8th grade. They asked the children to list their three closest friends.

While parental monitoring didn’t have a great effect on changes in academic performance over the years, it was linked to fewer behavior issues, which led the team to suggest that it may have a real, if "indirect", effect on academics.

The researchers assessed each student’s – and his or her friends’ – academic performance and behavior issues based on academic records. They used questionnaires to get at qualities like "school engagement" (how often the kids did their homework and cooperated with their teachers), and "parental monitoring" (the degree to which parents were generally involved in their kids’ lives).

As expected, kids whose friends were more socially "problematic" did worse academically than those whose friends had more positive behavioral characteristics. But when it came to friends’ academic performance, the relationship was more complicated — for girls at least. Girls who were more academically-minded and whose friends were the same way performed better than expected as time passed. But girls who started out as lower achievers did worse than expected over time if their friends were academically inclined.

The researchers weren’t totally surprised by these findings: earlier studies had shown that having "outperforming" friends can lead to a negative self-image, which in turn can lead to worse performance in school. In contrast, for kids who are higher achievers to begin with, having friends who are the same way may cause an even greater desire to achieve. Similar relationships between friends’ academic performance and one’s own were not seen in boys, which the authors also say makes sense, since boys are typically not as driven by "social approval" as girls are.

While parental monitoring didn’t have a great effect on changes in academic performance over the years, it was linked to fewer behavior issues, which led the team to suggest that it may have a real, if "indirect", effect on academics.

There are some drawbacks the study, like the fact that other variables, such as socioeconomic status, education level of the parents, and how important the kids perceive education to be, were left out. Also important is the fact that friends’ behavioral and academic characteristics were only looked at in 6th grade, not 8th, so it is possible that circles of friends may have changed over the years. Future research will need to take these issues into account for a fuller grasp of all the mechanisms that lead to kids performing well or poorly in school.

In the meantime, it’s probably wise to know who your kids’ friends are, and notice if there are changes in the "type" of friend your child chooses. Talking to your child and/or his or her teacher or school counselor may be a good idea if you have concerns.

The study was carried out by researchers at the University of Oregon, and published in the February 2011 issue of The Journal of Early Adolescence.