A case study of clinical practice in children with glue ear is presented. The case is part of a larger project, funded by the North Thames Research and Development Programme, that sought to explore the part played by clinicians in the implementation of research and development into practice in two areas: adult asthma and glue ear in children.What is striking about this case is the diVerences found in every area of the analysis. That is, diversity was found in views about diagnosis and treatment of glue ear; the organisation of related services; and in the reported practice of our interviewees, both between particular groupings of clinical staV and within these groupings. The challenge inherent in the case is to go beyond describing the complexity and diVerences that were found, and look for patterns in the accounts of practice and tease out why such patterns may occur. (Quality in Health Care 1999;8:108-118) Keywords: case study; glue ear; evidence; practice There is growing interest in the potential benefits promised, both quality and the use of resources, by more eVective implementation of evidence emanating from biomedical research and development. In the context of the UK NHS, this interest is evident in the discussions of evidence-based medicine and the more recent NHS policy initiatives that have created an array of organisational structures and processes designed to improve clinical effectiveness. The success of such national initiatives will be judged by the extent to which they result in significant change in clinical practice in line with the "evidence". Little is known, however, about how clinicians change their practice and, in particular, what the key influences are that shape clinical practice. The case study presented here is part of a research project designed to understand the social context in which decisions about clinical care are made in the UK NHS context, 1a 1 and to identify the factors which clinicians in primary and secondary care see as encouraging or discouraging the development of evidence-based practice.The research strategy used was based on comparative case studies. 1 An important advantage of this method is that it aVords an opportunity for an holistic view of a process. Drawing on traditional methodologies associated with case studies (interviews, questionnaires, documentary analysis, and participant observation), we were able to generate rich descriptive accounts of approaches to clinical practice and improve our knowledge of the social and organisational context in which clinical practice occurred. The case study method also allowed us to capture and control for the eVects of several organisational variables thought to impinge upon clinicians' decision making and the diVusion of research and development findings.The project focused on clinical behaviour and attitudes associated with the diagnosis of two conditions: adult asthma and glue ear in children. The conditions were chosen for their ordinariness as commonly occurring within the routine clinical experience of ...