The sixteen papers in this volume are representative of Mr. Johnson's intense study of the theory of tariffs during the past decade. Included is a newly written critique of the theory of effective protection—a recent development which is revolutionizing both the measurement of tariff heights and the whole approach to international tariff-making at the policy-making level. The text also covers the positive theory of tariffs, the theory of the costs of protection, and the effects of tariffs when domestic distortions are present. The final section deals with the problems of harmonization of policy in free trade associations.