We analyze the effects of a unique forest conservation regulation on residential development and assess the additionality in forest cover due to this regulation. We combine panel data on forest cover change from satellite imagery and parcel-level modeling on residential development, including residential subdivisions occurring before and after regulation adoption. Our results indicate that after introducing the regulation, there was a 22% increase in forest cover within subdivisions relative to the amount without the regulation. The heterogeneous effects of this regulation suggest that forest cover increased on average for parcels with lower levels of existing forest cover. However, parcels with the highest levels of forest cover continue to have significant decreases in forest cover, despite the regulation, thereby resulting in fragmentation in regions with the most intact forest cover.