In order to explain two-way trade, the standard H-O model has recently been modified by assuming a market structure with monopolistic competition. The factors that affect the volume of total trade and its intra-industry component in the 2 x 2 model have been specified in these papers. This paper generalizes these results to the N-good, M-country case. Although endowment similarity increases the intra-industry component in the 2 x 2 case, this proposition does not strictly hold for bilateral trade in the N x M case. Similarity of relative income size (GNP) does increase intra-industry trade in the 2 x 2 case, but does not increase the intra-industry share as assumed by several authors. In the N x M case, similarity of relative income size does not affect the bilateral volume of intra-industry trade nor its intra-industry share. This article thus shows that ceteris paribus comparative static changes in income size in a 2-country model are not equivalent to changes in that variable across a cross-section of a multi-country model.