The aim of this paper is to contribute to understanding the nature of specialist and generalist human capital by exploring the ways in knowledge workers view their experience of working in specialist and generalist roles in pharmaceutical firms in Ireland and the UK. The findings are based on interviews with 55 knowledge workers employed in a range of scientific, technical and managerial positions in four Irish and two UK firms located in the pharmaceutical sector. Interviews were also conducted with nine human resource/training and development managers within these six firms. The findings suggest that the categorisation of human capital as either specialist or generalist is too rigid and does not take account of the fact that individuals may themselves choose to shape their careers by investing in a range of education, training and development opportunities that will enable them to move between specialist and generalist roles. The paper unpacks the concepts of specialist and generalist human capital from an employee perspective and challenges the sharp distinction that is made between specialist and generalist human capital.