In this paper, we discuss qualitative research for public health professionals. Quality matters in qualitative research, but the principles by which it is judged are critically different from those used to judge epidemiology. Compared to quantitative research, good quality qualitative studies serve different aims, answer distinct research questions and have their own logic for sampling, data collection and analysis. There is, however, no need for antagonism between qualitative research and epidemiology; the two are complementary. With theoretical and methodological guidance from experienced qualitative researchers, public health professionals can learn how to make the most of qualitative research for themselves.