Professionalisation has been a process which has profoundly influenced the societies of the most industrialised countries, since it entails a high position in the occupational hierarchy for its members. This has marked effects on the occupational choices of individuals, because the social prestige accorded to an occupation is an important part of the total reward accruing from it. This paper analyses the economic consequences of the phenomenon, concentrating in particular on the effects of technological innovation. The argument put forward is that professionalisation may hamper the diffusion of innovative technologies because it makes the choice of the new professions less attractive. Moreover, it renders the management of high-skilled workers costly for firms, since innovative firms must adopt new technique of human resource management. To the extent that these professions are complementary to the new technologies, their reduced supply and the high cost of their management may be a serious obstacle against the diffusion of technological innovation.