This comprehensive discussion of international trade theories focuses on logically distinct models of international trade rather than on chronology or “schools of thought.” The author gives primary attention to the differences in the empirical implications derivable from the “Heckscher-Ohlin model” and from the simple classical comparative models of international trade. He also emphasizes the recurrence of controversy over matters of aggregation, due to the lack of a common criterion, and the rich variety of model types that result from dynamic theorizing, discrediting the search for an ultimate dynamic international trade model. This book is intended especially for teachers and graduate students who require a broad understanding of basic theories in the field.