With a growing global population, much of the current discourse on food security is focussed on increasing agricultural production. However, studies suggest that food insecurity is not caused by lack of food production, but by inadequate distribution, a lack of purchasing power and other non-productive causes. This paper argues that forests and tree-based agricultural systems contribute directly and indirectly to the livelihoods of an estimated one billion people globally. Despite this, the role of forests in supporting human food security and nutrition remain largely under-researched and understood. Although existing evidence is limited, a considerable body of work suggests that forests support both food security and nutrition. The authors argue that there is now an urgent need for research that can provide broader perspectives and allow of cross-site comparisons of the contributions of forests and tree-based agricultural systems to food security, livelihoods and nutrition.