This chapter provides a rationale for the book and the research that it presents. It documents the near complete absence of prior research into teacher or teaching quality in the global South and justifies specifically why teacher expertise research may be the most useful vehicle through which it can be studied. It argues that the contextually appropriate, feasible and sustainable pedagogic practices of expert teachers in any context can, if implemented more widely across the educational system, bring about significant increases in the quality of teaching and learning. The chapter offers a definition of ‘global South’ specific to the aims and contexts of the book and compares this with alternative ways of conceptualising the South. My background, as author of this book, is then presented, followed by an overview of the book that includes brief summary descriptions of the chapters that follow. The chapter finishes with a discussion of paradigmatic concerns that sets out the author’s own position as a multiple- methods, critical realist researcher who rejects the paradigm dichotomy between positivist and interpretivist approaches, instead preferring to view generalising and particularising tendencies in research through a continuum along which researchers are able to move flexibly, appropriate to the questions or problems of interest under investigation.