Despite the growing popularity of free college proposals, countries with higher college subsidies tend to have higher enrollment rates but not higher graduation rates. To capture this evidence and evaluate potential free college policies, we rely on a dynamic model of college enrollment, performance, and graduation estimated using rich student-level data from Colombia. In the model, student effort affects class completion and mitigates the risk of performing poorly or dropping out. Among our simulated policies, universal free college expands enrollment the most but has virtually no effect on graduation rates, helping explain the cross-country evidence. Performance-based free college triggers a more modest enrollment expansion but delivers a higher graduation rate at a lower fiscal cost. While both programs lower student uncertainty relative to the baseline, performance-based free college does it to a lower extent, which in turn promotes better student outcomes. Overall, free college programs expand enrollment but have limited impacts on graduation and attainment due to their limited impact on student effort.