Chapter four provides an overview of qualitative comparative analysis (QCA), the methodological approach used in this book. QCA is a valuable analytical tool for cross-country analysis and enables nuanced, comparative analysis of international welfare regimes. The chapter sets out the main characteristics of QCA as a methodological approach and how it acts as a bridge between theory and empirical analysis, which is essential when considering the potential effects of basic income. It sets out the key concepts used in QCA and how they will be used later in this book. This methodological bridge between theory and empirical analysis allows a systematic examination of how basic income principles manifest in real-world welfare systems, setting up the foundation for later analysis of their effects on job search behaviour.