This paper examines the long-run impact of Medieval and Early Modern universities on urban population growth in a panel of 2,262 European cities observed between 700 and 1800. Using a staggered difference-in-differences design with heterogeneous treatment timing, we estimate the effect of university establishment on city population. We find positive and statistically significant effects between 1200 and 1500, concentrated among early, high-quality institutions. Effects are stronger in cities close to major trade routes and persist longer in Atlantic areas, while fading earlier in Mediterranean regions, suggesting the importance of trade-related mechanisms.