Competition between firms to invent and patent an idea, or “patent racing,” has been much discussed in theory, but seldom analyzed empirically. This article introduces an empirical way to identify patent races, and provides the first broad-based view of them in the real world. It reveals that patent races are common, particularly in information-technology fields. The analysis is then extended to get the causal impact of winning a patent race, using a regression-discontinuity approach. It shows that patent race winners do significantly more follow-on innovation, and the follow-on research that they do is more similar to what was covered by the patent.