The paper develops a conceptual framework aimed at analyzing the profitability of financing general training, based on the notion of complementarity among productive factors. First, we show that a simple application of the theoretical analysis based on the lattice theory and the notion of supermodularity can provide a suitable framework for studying the complementarity relationships characterizing the productive factors. Second, we discuss empirical evidence on complementarity between general and specific training with respect to firm productivity, exploiting a detailed and specifically constructed survey based dataset. Complementarity between training forms is, thus, tested in a discrete framework. We show that complementarity holds for most specifications, though the outcome might be dependant on other firm-related features and strategies. The multivariate analysis also shows, on the same model framework, that R&D and training expenditures are emerging as the main explanatory drivers for productivity. Our results on training complementarity and productivity drivers indicate that complementarity related to training forms matters, however, mere training adoption is probably not sufficient: the level of training provided is positively correlated with firm productivity.