The movement towards blending qualitative and quantitative methods in health services research is now well established. Models for blending the two include a hierarchical approach, in which one or other approach dominates, and a partnership model featuring more equal (albeit differing) roles for each. The partnership model may involve simultaneous or sequential application of qualitative and quantitative methods. For each model, the ideal is to blend qualitative and quantitative approaches to take advantage of the particular strengths of one approach in compensating for known limitations in the other under particular circumstances. The optimal blend varies at different stages of the research process, from conceptualizing the study through data collection and analysis, to interpreting the results.