Community seed banks (CSBs) are initiatives to support the conservation and use of diverse crops though locally rooted collective action. The impact of CSBs is assumed to be complex, but has not been investigated in detail. Our study addresses this gap by analysing the impact of CSBs using social-ecological resilience as theoretical framework. We focus on the western highlands of Guatemala where CSBs have been implemented since 2009. We used qualitative and quantitative methods of data collection and analysis, including focus groups, participatory workshops, and structured and semi-structured interviews conducted in the local communities with CSB members and non-members. Our results indicate that CSBs contributed to increased seed exchanges, improved access to novel crop diversity, more saving of traditional varieties, and greater information and knowledge access, use and exchange. These effects strengthened the social-ecological resilience of the local communities. The scope of action of the CSBs, however, was constrained by wider socio-economic trends, including social divisions, out-migration of youth, and a change in livelihood strategies. We conclude that for CSBs to effectively strengthen social-ecological resilience in the future, they should be continuously adapted to the local context. Conceptually, our findings call for the further evolution of the CSB concept.