The diffusion and use of new ideas is critical for producing innovations and realizing their potential. We explore how characteristics of innovators and potential adopters affect the adoption of important, new scientific ideas in networks. Using rich data on biomedical researchers and their networks, natural language processing, and a novel two-way fixed effects strategy, we find that new ideas introduced by female scientists are underutilized for two reasons. First, female innovators are less connected than men. Second, at short network distances, researchers (especially men) adopt women’s ideas less. Similar gaps hold for underrepresented racial and ethnic minorities.