This book takes an historical view to explain how social science arrived at its current state and proposes solutions to its problems. This book shows the reader that theory is the method of the sciences. First it explains how the empiricism of J. S. Mill and R. A. Fisher has blocked the growth of theory-driven research. The myths of how science works, as proposed by T. Kuhn, have added another layer of obfuscation. Wholesale adoption of empiricist methods has produced the replication crisis – that most experimental findings cannot be replicated in economics and psychology and undoubtedly also in sociology. Without theory, the scope of research topics has constricted, resulting in what R. Merton feared, a balkanization of knowledge in sociology.  Then, having cleared the intellectual underbrush, the book turns to how theory-driven experiments are constructed. Fortunately, today a number of theory-driven experimental studies are found in the literature. This book's use of those studies as examples will help the reader understand this form of experimentation. The authors envision an explanatory sociology in which experimentally grounded theory forms a ‘toolbox’. The parts of the toolbox are deployed to explain complex historical and contemporary events. Here examples are few and far between: we will need to build new ones.  Taken together, this book envisions a radically changed social science, and it is vital reading for scholars across sociology, political science, economics, and social psychology.