Increased temperatures and shorter periods of rainfall induced by global climate change are generating shorter and more unpredictable growing seasons for East African farmers. This study investigates how information and genetic diversity flows through social networks in Kenya and Uganda helping smallholder farmers adapt to climate change. Drawing on detailed household survey data collected in 2016 by Bioversity International from over 600 households we summarize farmers' current seed sources and current climate adaptation strategies, and identify sources of new seed and information. Using UCINET statistical software we then model the networks of seed and information exchange within and across communities, characterizing seed and information networks by country, gender, and crop. Findings suggest that farmers in Kenya and Uganda have a strong dependence on localized seed systems (e.g., own-saved seed and farmer-to-farmer exchanges of seed) and have only weak ties to formal seed systems (e.g., commercial seed producers). Climate change is a widely recognized threat to farmer livelihoods, with nearly all respondents indicating that they experience climate related challenges. Farmer field days and agri-shows were listed as the main sources of new seed and climate change adaptation information by many respondents. In terms of social networks, female farmers on average have larger and denser networks for seed and information exchange, and farmers in Kenya tend to have more extensive networks than farmers in Uganda. Many respondents in both countries were involved in farmer organizations, with these organizations providing access to seed and access to information about climate change adaptation. Overall, results indicate that there are many ways to support improved access to seed and climate change adaptation information in Kenya and Uganda. Directing policy efforts and resources towards informal seed systems, including local markets, farmer organizations, and seed fairs, may prove most effective for reaching rural smallholders and women in particular.