This paper examines the relationship between trade volume and composition in fourteen industrial countries during the post-war period, using models of monopolistic competition in differentiated products. The study tests three empirical hypotheses derived from these models: (1) the volume of trade is influenced by differences in factor composition; (2) the share of intra-industry trade is affected by differences in factor composition; and (3) the volume of trade is related to relative country size. The findings suggest that trade volume is more closely related to differences in factor composition than to relative country size, while the share of intra-industry trade is more closely related to differences in factor composition and relative country size. The study also finds that the share of intra-industry trade is negatively correlated with income per capita dispersion, supporting the hypothesis that more similar countries have higher intra-industry trade shares. The results are consistent with theoretical models of trade in differentiated products and provide evidence that trade volume and composition are influenced by factors such as factor composition and relative country size. The study also highlights the importance of using disaggregated data and considering both manufacturing and non-manufacturing industries in trade analysis. The findings suggest that the relationship between trade volume and composition is complex and influenced by a variety of factors, including economic structure, factor composition, and country size. The study provides important insights into the determinants of trade volume and composition and supports the theoretical models of trade in differentiated products.This paper examines the relationship between trade volume and composition in fourteen industrial countries during the post-war period, using models of monopolistic competition in differentiated products. The study tests three empirical hypotheses derived from these models: (1) the volume of trade is influenced by differences in factor composition; (2) the share of intra-industry trade is affected by differences in factor composition; and (3) the volume of trade is related to relative country size. The findings suggest that trade volume is more closely related to differences in factor composition than to relative country size, while the share of intra-industry trade is more closely related to differences in factor composition and relative country size. The study also finds that the share of intra-industry trade is negatively correlated with income per capita dispersion, supporting the hypothesis that more similar countries have higher intra-industry trade shares. The results are consistent with theoretical models of trade in differentiated products and provide evidence that trade volume and composition are influenced by factors such as factor composition and relative country size. The study also highlights the importance of using disaggregated data and considering both manufacturing and non-manufacturing industries in trade analysis. The findings suggest that the relationship between trade volume and composition is complex and influenced by a variety of factors, including economic structure, factor composition, and country size. The study provides important insights into the determinants of trade volume and composition and supports the theoretical models of trade in differentiated products.