What happens if you expand higher education?

This is based on Italian data from the 1960s:

However, I also find that those induced to enroll earned no more than students in earlier cohorts who were denied access to university. I reconcile these surprising results by showing that the education expansion reduced returns to skill and lowered university learning through congestion and peer effects. I also demonstrate that apparently inframarginal students were significantly affected: the most able of them abandoned STEM majors rather than accept lower returns and lower human capital.

Uh-oh.  The good news, however, is that the children of these individuals seem to have ended up in higher-paying jobs.

That is from Nicola Bianchi (pdf), he is now at Northwestern.  For the pointer I thank Robin Gaster.