Using evidence from a sample of over 800 leases, this paper examines the productivity of farming in the Paris Basin between 1450 and 1789. Existing evidence about productivity is unreliable, the paper argues, and the leases provide historians with a new and valuable source for the study of productivity and economic growth. Much of the paper is devoted to a defense of the method employed with the leases, which point to spurts of spectacular growth on local farms but also to stunning setbacks during times of war and increased taxation. The paper concludes with analysis of the causes of economic growth in pre-industrial agriculture.