The case study approach allows in-depth, multi-faceted explorations of complex issues in their real-life settings. It is widely used in business, law, and policy but less so in health services research. This paper discusses the different types of case study designs, the research questions they can address, data sources, and their advantages and disadvantages. It also provides key pointers for designing and appraising case study research and a checklist for assessing the quality of case study reports. Case studies are particularly useful when in-depth understanding of an issue, event, or phenomenon is needed in its natural context. They can be used to describe a patient's care episode, explore professional attitudes towards new policies, or investigate contemporary phenomena in real-life settings. The paper draws on examples of case studies to illustrate the methodological considerations involved in case study research. Case studies can be intrinsic (to understand a unique phenomenon), instrumental (to gain broader understanding of an issue), or collective (to study multiple cases simultaneously). The paper discusses the importance of theory in case study design, selection, conduct, and interpretation. It also highlights the different epistemological approaches used in case study research, including critical, interpretivist, and positivist perspectives. The paper outlines the main stages of case study research: defining the case, selecting the case(s), collecting and analyzing data, interpreting data, and reporting findings. It emphasizes the importance of defining the case clearly, selecting cases that are relevant and hospitable to the inquiry, and ensuring access to the case study site. Data collection typically involves multiple sources, including quantitative and qualitative methods, to increase the validity of the study. Analysis and interpretation of case study data require careful attention to variations within each case and the relationships between different causes, effects, and outcomes. The Framework approach is a practical method for managing and analyzing large datasets. The paper also discusses potential pitfalls of case study research, such as lack of scientific rigor and difficulty in generalizing findings, and suggests ways to address these issues, including theoretical sampling, respondent validation, and transparency in the research process. The paper concludes that case study research is a valuable method for studying complex health service issues in real-life contexts. It should be considered when experimental designs are inappropriate or impossible. The case study approach can provide powerful insights into important aspects of health and healthcare delivery if carefully conceptualized and reported.The case study approach allows in-depth, multi-faceted explorations of complex issues in their real-life settings. It is widely used in business, law, and policy but less so in health services research. This paper discusses the different types of case study designs, the research questions they can address, data sources, and their advantages and disadvantages. It also provides key pointers for designing and appraising case study research and a checklist for assessing the quality of case study reports. Case studies are particularly useful when in-depth understanding of an issue, event, or phenomenon is needed in its natural context. They can be used to describe a patient's care episode, explore professional attitudes towards new policies, or investigate contemporary phenomena in real-life settings. The paper draws on examples of case studies to illustrate the methodological considerations involved in case study research. Case studies can be intrinsic (to understand a unique phenomenon), instrumental (to gain broader understanding of an issue), or collective (to study multiple cases simultaneously). The paper discusses the importance of theory in case study design, selection, conduct, and interpretation. It also highlights the different epistemological approaches used in case study research, including critical, interpretivist, and positivist perspectives. The paper outlines the main stages of case study research: defining the case, selecting the case(s), collecting and analyzing data, interpreting data, and reporting findings. It emphasizes the importance of defining the case clearly, selecting cases that are relevant and hospitable to the inquiry, and ensuring access to the case study site. Data collection typically involves multiple sources, including quantitative and qualitative methods, to increase the validity of the study. Analysis and interpretation of case study data require careful attention to variations within each case and the relationships between different causes, effects, and outcomes. The Framework approach is a practical method for managing and analyzing large datasets. The paper also discusses potential pitfalls of case study research, such as lack of scientific rigor and difficulty in generalizing findings, and suggests ways to address these issues, including theoretical sampling, respondent validation, and transparency in the research process. The paper concludes that case study research is a valuable method for studying complex health service issues in real-life contexts. It should be considered when experimental designs are inappropriate or impossible. The case study approach can provide powerful insights into important aspects of health and healthcare delivery if carefully conceptualized and reported.