Voluntary carbon markets provide a unique opportunity to diversify climate funding streams for small-scale agriculture. However, due to the emerging nature of regulation in voluntary carbon markets, the projects’ transparency, scope, and quality of engagement with smallholder farmers to ensure adoption is highly variable. PxD set out to improve the market’s understanding of how projects should work with farmers to ensure adoption of the sustainable agriculture practices necessary for achieving carbon outcomes. PxD used qualitative research on smallholder farmers participating in ongoing carbon credit projects, engagement with key stakeholders in an advisory group, and desk research to develop insights into the best practices for engagement with smallholder farmers, in order to strengthen the market for agriculture-focused carbon credit projects in low- and middle-income countries. Notably, we find that project co-benefits, which are additional benefits from a project beyond its GHG emissions outcomes, such as productivity increases and access to agricultural services, are farmers’ primary motivation for project participation, rather than cash incentives from carbon credit revenue sharing. Our findings suggest best practices include incorporating co-benefits into the carbon credit project’s theory of change, involving all project stakeholders in operationalizing the project’s theory of change, and connecting co-benefit measurement with carbon monitoring, reporting, and verification (MRV) systems.