We study the effect of an agricultural conservation policy on biodiversity in Switzerland. The policy aims at coordinating farmers conservation efforts and grants them a subsidy if they create spatially contiguous protected areas. We assemble a unique geo-referenced dataset that links information on farms’ structure and policy participation to a rich biodiversity dataset that spans over a century and contains more than 100,000 of species observations. The data allows us to observe hundreds of regional coordination games. Using the staggered policy introduction across regions as a source of identifying variation, we find that the policy substantially improved coordination and increased biodiversity up to 55%.