This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book addresses the equally important enterprise of how the discovery of theory from data—systematically obtained and analyzed in social research—can be furthered. It deals with beginning formulation of some of the processes of research for generating theory. The book discusses theoretical sampling—the process of collecting data for comparative analysis designed to generate substantive and formal theory. It offers method for the comparative analysis of qualitative data. The book also discusses the contemporary emphasis on verification, the influential style of logico-deductive theorizing, which encourages the drive toward verification, and the distinction usually drawn between qualitative and quantitative data—a distinction useless for the generation of theory. Students are trained to master great-man theories and to test them in small ways, but hardly to question the theory as a whole in terms of its position or manner of generation.