I examine the impact of gender-neutral custody laws on divorce. I develop the first systematic
coding of custody law changes over the twentieth century and show that states’ movement from
maternal preference to gender-neutral custody laws is independent of the adoption of unilateral
divorce laws. I exploit the variation across states in the timing of the legal changes to identify the
effect of the new custody law on divorce. I find that changes in custody laws have a dynamic
effect on divorce rates. The divorce rate begins to increase approximately seven years after a
state’s adoption of the new custody law and persists thereafter. The magnitude of the increase is
between 0.1 and 0.2 divorces per 1,000 people per year. Changes in custody laws also increase
the likelihood of being separated by roughly 0.5 percentage points for women and 0.3 percentage
points for men. The effects I find for changes in custody laws are independent of those of
unilateral divorce. The results suggest that child custody law reform play an important and
overlooked role in marital dissolution in the U.S.