This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book analyzes farm-level data from four low-income sub-Saharan African countries to gain insight into possible reasons for the low adoption of modern productivity-enhancing inputs, such as inorganic fertilizers and improved seeds, by Africa's mostly smallholder farmers. It uses data from five sub-Saharan African countries to examine the robustness of the negative relation between farm size and productivity that is often observed in empirical studies. The book also examines the options for enabling smallholders to gain access to yet unexploited lands, where they have a potential for high productivity only if the infrastructure of such regions is developed. It reviews the predictions and policy relevance of agricultural evolution theory, a key area of Hans Binswanger's research contributions. The book discusses another important focus of Hans Binswanger's research – namely, policies to enhance land tenure security and to improve the efficiency of land markets.