This document outlines a protocol for conducting a yield gap survey in Africa. It begins by defining types of yield gaps and explaining the importance of studying yield gaps to increase food supply and identify constraints on production. It then reviews previous yield gap studies in Africa and their limitations. The proposed protocol involves selecting fields across agroecological zones, conducting regular field observations and crop management interviews, and follow-up interviews after harvest to identify constraints. The goal is a multidisciplinary study of biophysical and socioeconomic factors contributing to yield gaps across multiple African countries.