The paper deals with some aspects related to the changes in the organization of work that took place within the supposed shift from the "taylor-fordist" paradigm to new productive models. Literature review shows that, while the effects of new work practices on employees' welfare are still not clear, the positive impact on firms' economic, financial and productive performances seems quite evident. So, one can assume that the limited expansion of new work practices isn't caused by employers' scepticism on their effectiveness. The thesis of the paper is that firms structural and market variables play a determinant role in distinguishing "innovative" from "conservative" firms. Confirming a large part of the hypothesis existing in literature, multivariate discriminant analysis shows that innovative firms characterize themselves for more intense relationship with other firms, for higher degree of technological innovation and for higher degree of market competitiveness. From the industrial relations side results are less clear: on one side innovations in organization of work are more diffused in firms that have a formal workplace union representation; on the other side, where the level of unionization is high the adoption of innovative work practices is less widespread.