Will You Marry Me, Later?

We examine the impact of raising the minimum age of marriage to 18 years old in Mexico. Using a difference-in-differences model that takes advantage of the staggered adoption of this reform across states, we find a large reduction in the number of registered child marriages. However, we find no effect on school attendance or early fertility rates. We provide evidence that this is driven by a substitution of formal marriage for informal unions. This suggests that when informal unions are a viable option for young couples, age-of-marriage reforms are not enough to prevent early unions and their negative consequences.