A case-study of relations between supervisors and workers in a medium-sized shoe factory is used to argue that it is the Marxian question of function within the social relations of production rather than the Weberian one of market capacities which most convincingly determines the question of the proletarianization or otherwise of the direct supervisors of labour. Understanding class, and therefore proletarianization, as a matter of the interests arising out of the social relations of production, it is shown that, for the supervisors, these were not changed by a deterioration of their position on such Weberian dimensions of stratification as income and status relative to the workforce, nor by a diminution of their decision - making power within the management function. Rather, the supervisors responded to their situation by attempting to demonstrate their continuing usefulness as the extractors (rather than the creators) of surplus value since it was by these standards that their worth was judged - and increasingly doubted. The `option' of maintaining their position by playing a greater role in assisting the productive process itself was effectively foreclosed by technological and organizational developments in which assistance of a nature sufficiently demanding to justify a supervisory position was either beyond the capacity of the supervisors or had already been taken over by experts. Although the supervisors resented their low pay, lowly status and the pressures put upon them by senior management, their interests clearly lay in continuing to serve the interests of capital within the social relations of production. There was therefore no question of their proletarianization in the sense outlined above.