Although qualitative research methods have grown increasingly popular,confusion exists over how their quality can be assessed and the idea persists that qualitative research is of lesser value when compared to quantitative research. Quantitative and qualitative research have different historical roots and are based on very different concepts, yet the dominance of positivist ideas about what constitutes good quality, valid research in psychology has often led qualitative research to be evaluated according to criteria, that are designed to fit a very different paradigm. Inevitably, the diverse perspectives which use qualitative methods and their differing views on how people should be studied mean there is disagreement and controversy over how quality should be evaluated. Despite this, it is seen as important to develop common criteria which allow the quality of qualitative research to be evaluated on its own terms.