Based on the notion of complementarity among productive factors, the paper develops a conceptual framework aimed at analysing why a firm may find it profitable the financing of general training. The paper shows that a simple application of some contributions of theoretical analysis based on the lattice theory and the notion of supermodularity can provide a suitable framework of analysis to study and understand complementarity relationships which can be established among productive factors. Especially, the paper develops the analysis of complementarities between general and specific training providing, additionally, a theoretical reference for empirical analysis.