This study analyses firms’ offshoring strategy from an empirical perspective. It focuses on market thickness, firm heterogeneity and the relative costs of organisation modes. This study focuses on a set of theoretical predictions and creates a set of suitable variables to test their validity. This analysis is based on a data set from French manufacturing firms that provides detailed information on their offshoring strategy. The choice of offshoring modes is investigated through the estimation of a multinomial logit model and related to a set of explanatory variables at firm, industry and country level. The results emphasise the role of firm heterogeneity, asset specificity and of market thickness.