The pursuit of food security is often the main reason behind the conversion of forests to farmland – even when those forests provide food for many rural households. Two million poor people live in such environments in the case-study regions of Colombia and Malawi alone, with a further 550 million people globally who are similarly impacted. The overarching goal of this research is to explicitly quantify the linkages between the natural ecosystem services that affect – and are affected by – food security and nutritional health for the rural poor that live along forest–agricultural margins.