This accessible book offers a detailed guide to a wide range of methodological concepts, both those of a philosophical kind and those that are more technical in character: from constructionism to critical realism, grounded theory to regression analysis, odds ratios to triangulation. It covers quantitative, qualitative, and mixed methods research. There are shorter entries for relatively straightforward terms and longer entries for terms that are more complex or carry more than one meaning. The book includes basic terms – such as data, empirical, fact, meaning, theory, and truth – as well as those that highlight major contemporary trends in the field, such as arts-based research, indigenous methodologies, and decolonisation. It is therefore relevant to many methodological issues and controversies taught in social science degree programmes today. Providing clear definitions for a wide range of methodological concepts from across the social sciences, this is an essential resource for all who have an interest in social research methodology.