This review focuses on the two major psychosocial areas currently topical in cystic fibrosis research: treatment adherence and quality of life. First, the paper discusses the importance of evaluating adherence to treatments and medical advice, its measurement, predictors of adherence and non-adherence and whether the data should be used to inform clinical practice and policy decisions. Second, the purpose of evaluating quality of life in cystic fibrosis and an overview of the data are discussed. Both areas have suffered from problems with terminology and definition, inappropriate methodologies and hence difficulties with data interpretation. Future directions for research are advocated.