Between 2017 and 2021, Spain progressively extended paternity leave from 2 to 16 weeks, equalizing it with maternity leave and introducing mandatory weeks. A 2018 reform also allowed fathers to split their leave. Using administrative data on all leave permits since 2016, we analyze trends in paternity leave take-up. Following the introduction of mandatory leave, the share of fathers taking leave increased by around 20 percentage points, and most now use nearly the full entitlement. The share opting to split leave has steadily grown, surpassing 50% by 2023. However, this behavior shows marked heterogeneity: while overall uptake is uniform across groups, leave-splitting is far more common among higher-income fathers and more prevalent in certain sectors. Spain's experience illustrates how policy design can significantly increase paternity leave usage, though workplace flexibility and income-related constraints shape how fathers use that time.