[Excerpt from author] As many countries initiate health sector reform-led cost containment and quality improvement measures, there is an increasing need for health care organisations to identify the most appropriate mix of staff. This paper examines why achieving the right mix is so important, critiques the main approaches used in determining personnel mix in health care, and discusses the main lessons from research in this area. The paper discusses eight methods of determining personnel mix: task analysis, activity analysis, self recording of activities, case mix/dependency, zero-based reprofiling, professional judgement, job analysis interviews, and group brainstorming. Methods of evaluating cost effectiveness are also considered. In reviewing relevant research in this area the authors provide a conceptual model of the elements involved in determining skill mix.