This paper exploits the introduction of the first regularized patent system, which appeared in the Venetian Republic in 1474, to examine the factors shaping inventors' propensity to use a new form of intellectual property right. We begin by developing a model that links patenting activity of craft guilds with provisions in their statutes. The model predicts that guild statutes that are more effective at preventing outsiders' entry and at mitigating price competition lead to less patenting. We test this prediction on a new dataset that combines detailed information on craft guilds and patents in the Venetian Republic during the Renaissance. We find a negative association between patenting activity and guild statutory norms that strongly restrict entry and price competition. We show that guilds that originated from medieval religious confraternities were more likely to regulate entry and competition, and that the effect on patenting is robust to instrumenting guild statutes with their quasi-exogenous religious origin. We also examine how patent strategies are related to other local economic and political conditions. Our analysis shows that the heterogeneity in patenting activity documented by the industrial organization literature is not a special feature of modern technologies, but is rather a persistent phenomenon affected by market power.