This chapter examines and critiques the theory of free trade, seeking to understand both the power of the theory and its limitations. The first section briefly presents the theory of free trade and offers and interpretation of its claim to scientific rigor. The second section surveys the theoretical critiques of free trade, and the third section reviews the reliance on protectionism in leading cases of industrial development in the past. The fourth section describes the neoliberal policies that have often been imposed by international institutions, and the disappointing evidence on their results. A final section offers concluding thoughts on alternative approaches to trade and development.