Increasing access to education may have consequences that go beyond effects on marginal students encouraged to enroll. It may change peer effects, school quality, and returns to skill. This paper studies how classmates and teaching inputs affect learning of university students, exploiting an educational expansion in Italian STEM majors. Newly collected data on 27,236 students indicate that less prepared classmates and congestion of teaching resources lowered learning of incumbent students in STEM fields. Their learning, however, increased in courses in which the new classmates raised average preparedness. These effects might have had long-lasting consequences on the returns to STEM degrees.

This article studies career spillovers across workers, which arise in firms with limited promotion opportunities. We exploit a 2011 Italian pension reform that unexpectedly tightened eligibility criteria for the public pension, leading to sudden, substantial, and heterogeneous retirement delays. Using administrative data on Italian private-sector workers, the analysis leverages cross-firm variation to isolate the effect of retirement delays among soon-to-retire workers on the wage growth and promotions of their colleagues. We find evidence of spillover patterns consistent with older workers blocking the careers of their younger colleagues, but only in firms with limited promotion opportunities.