Common beans (Phaseolus vulgaris L.) are a major subsistence crop in sub-Saharan Africa. Due to their capacity to fix atmospheric nitrogen, they are a very important source of dietary protein for the population and contribute to soil fertility. Nonetheless, common beans are known to have a low productivity and a high variability in yields. A better understanding of what causes this variability is necessary to adopt the right practices that will enhance the productivity of common beans.