Introduction.- International Trade in the Real World and the Theoretical Issues.- Economic Methodology.- The Classical View: Specialisation and Exchange, Absolute and Comparative Advantage.- Sources of International Trade: an Overall View.- The Ricardian Hypothesis.- Empirical Tests of the Ricardian Hypothesis.- The Heckscher-Ohlin Hypothesis.- The Heckscher-Ohlin Model Mathematically Treated.- Some Extensions of the Simple HOS Model.- Two Comparative Static Theorems.- The Ricardo-Viner Model.- Empirical Tests of HOS Hypothesis: the Factor Content Studies.- Empirical Tests of the HOS Hypothesis: the Cross-Section Studies.- Empirical Tests of the HOS Hypothesis: the Tests of Assumptions.- Two Theorems in Comparative Statics: the Rybczynski Theorem and the Findlay-Grubert Theorem.- International Trade and Economic Growth.- Trade and Growth Mathematically Treated.- A Dynamic Model of Capital Accumulation and International Trade.- The Neofactor Proportions Theories.- The Neotechnology Theory of International Trade.- Empirical Tests of the Neotechnology Hypothesis.- Views on Synthesis of the Neofactor Proportions and Neotechnology Hypotheses.- The Linder Hypothesis.- Intra-industry Trade: Imperfect Competition, Increasing Returns to Scale and Product Differentiation.- Empirical Studies in Intra-Industry Trade.- Endogenous Growth and International Trade.- Gains from Trade.- Trade Policy.- Economic Integration.