This book, authored by Laurent Levard, focuses on the economic concepts and methods essential for supporting agricultural development, particularly in the Global South. It delves into the fundamental economic units of agricultural production, addressing aspects such as opportunity cost, productivity laws, and the principles of economic rationality. The book offers tools for evaluating agricultural systems and activities, aiming to aid in the formulation and assessment of agricultural policies and projects. Designed for professionals involved in agricultural development, educators, and students in agronomy and economics, it provides a comprehensive framework for understanding agricultural diversity and economics. The work emphasizes the importance of tailoring interventions to the varied conditions and interests of different agricultural producers to achieve effective and sustainable outcomes.