According to researchers at Abilene Christian University, students who are active on Facebook are more likely to stay in school.
According to Wired, researchers following 375 first-semester freshmen at the university found that those who came back for sophomore year had a higher number of friends and wall posts than did those who left.
The article has more on the study's implications:
For other variables, Abilene Christian measured the number of Facebook groups joined and photo albums posted by the students, but the statistical differences were negligible.
Researchers determined that wall posts and the number of Facebook friends were the most significant predictors for determining a user's Facebook activeness, which in turn reflected their enthusiasm in the academic world surrounding them.
A similar study from Northwestern University found that Facebook does not necessarily affect student grades. Ars Technica details that factors like gender and ethnicity tend to influence GPA more than Facebook usage does.