We present a factor-proportions trade model in which heterogeneous firms can off shore intermediate inputs subject to fixed off shoring costs. In the skill-abundant country, high- productivity firms off shore a larger range of labor-intensive inputs to the labor-abundant countries than low-productivity firms. Differently from the traditional versions of factor-proportions trade theory, Heckscher-Ohlin forces operate at the within-industry level, leading to endogenous variation in skill intensity across firms that is positively correlated with firm productivity. Using French firm-level data for the years 1996 to 2007, we provide empirical support for the factor proportions channel through which offshoring to labor-abundant countries affects the firm-level skill intensities of French manufacturers.
