The paper develops a conceptual framework aimed at analysing the profitability to finance general training, grounding on the notion of complementarity among productive factors. First, we show that a simple application of theoretical analysis based on the lattice theory and the notion of supermodularity can provide a suitable framework to study complementarity relationships characterizing productive factors. Secondly, 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 multi variate analysis also shows, on the same model framework, that R&D and training expenditures are emerging as main explanatory drivers for productivity. Our results on training complementarity and productivity drivers indicates that complementarity related to training forms matters, but also that the mere training adoption is probably not sufficient: the level of training provided is positively correlated with firm productivity.