This chapter aims to explore how deeper knowledge of African farming systems structure and function can identify strategic interventions for sustainable agricultural intensification and contribute to poverty reduction and livelihood improvement. It considers farming systems to be substantial populations of individual farm households with broadly similar patterns of livelihood and consumption patterns, constraints and opportunities, and for which similar development strategies and interventions would be appropriate. More than 70% of the rural poor in sub-Saharan Africa reside in five broad regional farming systems being the focus of the chapter: the highland perennial, maize-mixed, cereal-root crop mixed, agro-pastoral and highland mixed farming systems. Effective sustainable intensification leads to productive diversified farming systems that maintain the resource base and respond to external opportunities and pressures from changing markets, population pressure and policies. Reversing the trend of soil fertility depletion, which governs agricultural productivity, in all African farming systems has become a major development policy issue.