An important distinction is that in Even and Smith’s sample, Greek-affiliated students had GPAs that were an average of between 0.1 and 0.2 points higher than non-Greek-affiliated students’ (which is a bit larger than the advantage that fraternities claim to have nationally). But that likely has more to do with the fact that the university in question required Greek-affiliated students to keep their GPAs above a certain level, and with the types of students who join Greek organizations in the first place—on average they are whiter and come from wealthier families than the students who don’t join. So fraternities and sororities’ members may get better grades, but that doesn’t mean fraternities and sororities make their members’ grades better. Instead, as Even and Smith found, Greek organizations likely make them worse.

The academic downsides of joining a Greek organization were especially large, Even and Smith found, during pledging, when hopefuls undergo “new-member education,” which often includes lots of drinking and sometimes includes hazing. (Even and Smith also noticed that during pledging, students were more likely to pick easier classes.) But in cases where students were suspended from their Greek organization as a result of a disciplinary action, their academic performance actually tended to start improving, in line with what the researchers would’ve predicted had those students not joined in the first place.

Even and Smith’s study didn’t pinpoint what it is about Greek organizations that might hurt their members’ grades (and it’s worth noting that Greek systems at other colleges might have slightly different cultures that could produce different results), but previous research provides a hint. A 2009 study found that Greek-affiliated students drink more than non-Greek-affiliated ones, and other studies have suggested that students’ grades tend to slip if they start drinking more than they did in their earlier college years.

What Greek organizations lose in academics, one could argue, they might make up for in improving their members’ job prospects, perhaps through strong professional alumni networks. Indeed, the students in Even and Smith’s sample tended to make more money—roughly 15 percent more—in their first job after graduation if they’d been in a fraternity or sorority. But that doesn’t mean Greek organizations are themselves the cause of their members’ increased earnings. Students who join the Greek system, Smith told me, tend to have higher-earning, better-educated parents. “And those types of students are probably more likely to have a higher salary early in their careers than those with lower socioeconomic status,” Smith said. After accounting for that, he and Even wrote in the paper that they found “no evidence of a Greek salary premium.”

Students in fraternities and sororities do seem to get better grades and go on to earn more money right out of college—but this research suggests it’s for reasons other than their membership in the Greek system. Their houses may actually be holding them back.

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