This course introduces the core theories and tools used to analyze international trade. In the first part, we develop the main trade models used to explain why countries trade and what determines trade patterns, including the Ricardian model, the Krugman model of increasing returns and monopolistic competition, the Specific Factors model, the HeckscherOhlin model, and the gravity model for understanding bilateral trade flows. In the second part, we study trade policy. We analyze the welfare and distributional effects of key trade policy instruments, such as tariffs and quotas. We also discuss the roles of trade institutions and agreements in historical context, as well as recent debates on trade wars and protectionism. In the final part, we cover selected advanced topics that connect trade theory to modern global economic questions, including trade and the labor market, the role of firms in the global economy, foreign direct investment and multinational production, and global supply chains. Throughout the course, we emphasize how to use disciplined economic reasoning to interpret real-world trade issues.

The goal of this course is to equip students with the core theoretical frameworks used in international trade and the ability to apply model-based reasoning to understand trade patterns and policy. The course also aims to prepare students to connect trade theory to major contemporary globalization issues. By the end of the semester, students are expected to be able to: • explain why countries trade and what determines patterns of specialization and trade flows; • work fluently with major trade models; • use economic reasoning to assess the welfare and distributional consequences of trade and globalization; • evaluate the effects of trade policy critically; • apply trade theory to real-world trade issues; and • communicate trade-theoretic arguments clearly, including assumptions, mechanisms, and policy implications.

During the course, students are expected to: • attend lectures and participate in class discussions; • complete problem sets (approximately every two weeks); and • take in-person midterm and final exams. Prerequisite: Students are expected to be familiar with introductory economics and basic calculus. Because the course relies heavily on constrained optimization and generalequilibrium reasoning, familiarity with intermediate microeconomics is strongly recommended but not required.

Required readings: There is no required textbook for this course. Lectures are based on lecture slides. A detailed reading list will be provided during the semester.

Optional background references (for self-study): • Krugman, P. R., Obstfeld, M., and Melitz, M. J. International Trade: Theory and Policy • Feenstra, R. C. and Taylor, A. International Trade