There are a wide range of agriculture-based practices and technologies that have the potential to increase food production and the adaptive capacity of the food production system, as well as reduce emissions or enhance carbon storage in agricultural soils and biomass. However, even where such synergies exist, capturing them may entail significant costs, particularly for smallholders in the short-term. In this paper, provide a brief review of the adaptation and mitigation benefits from various practices, and then focus in detail on empirical evidence concerning costs and barriers to adoption, both from household and project-level data. Findings indicate that up-front investment costs can be a significant barrier to adoption for certain investments and practices, and furthermore, the evidence also supports the hypotheses that opportunity and transactions costs across a wide range of investments and practices. Additionally, potential synergies between food security, adaptation and mitigation opportunities, as well as costs, can differ substantially across different agro-ecological zones, climate regimes, and historical land use patterns.