This article examines one of the core ideas in the human resource management rubric: that employers should seek to retain and develop their human resources, in particular professional personnel, since they are a source of competitive advantage. This idea is evaluated in the critical case of employers of technical staff. It finds, contrary to the prescriptive HRM literature, that employers were more concerned with having a steady turnover of staff, for which they saw a number of advantages, than with the development of policies which would enable them to retain scientists and engineers. These employers had, instead, developed a dual labour market approach which was contingent on the turnover of existing staff. This consisted of a general inclination to exploit the benefits of the prevailing labour market conditions while simultaneously engaging in a policy which allowed them to selectively retain certain key human resources.