Faith-based organizations (FBOs) have long played a role in international development, and are increasingly involved in environmental sustainability initiatives. Despite these contributions they have, until recently, been largely ignored in scholarship and by secular agencies. This article adds to the growing recognition of FBOs, exploring the identity and function of FBOs doing environmental and development work in Kenya through document review, qualitative questionnaires and participant observation. A diverse group of FBOs with varied identities and engaged in a broad range of activities revealed several strengths and challenges of faith-based environmental and development work. Of particular note is the key role churches and faith-based agencies can play in effecting sustainable and holistic change in Global South countries, due to their rootedness in the community, the social capital they help to produce, and the respect they receive from the people.