This study examines the effectiveness of the human resource management (HRM) function of a public sector entity as it became corporatized. There has been little empirical research regarding the effectiveness of the people management functions within the Australian public sector as these entities went through a period of transition to commercialization. A questionnaire obtaining perceptions on different aspects of HR effectiveness, both before and after corporatization, was administered to a sample (N = 122) representing a number of different stakeholder groups of the corporate HRM unit. The results showed a moderate, but statistically significant, improvement in the effectiveness of HRM, and of the corporate HRM unit, as the host organization went through corporatization. Perceptions on HR effectiveness were not found to vary significantly between the different stakeholder groups. Regression analysis showed that the major predictors of the improvement in the overall effectiveness of the corporate HR unit were, firstly, changes in the level of satisfaction with the quality of the HR outcomes as a result of commercialization and, secondly, the change in extent to which the senior HR practitioner had effective influence over strategic decision-making processes.