In this textbook, Derek Layder offers a better understanding of the links between theory and research, and provides an analysis of the relationship between the two. He develops clear usable strategies to encourage theory development in the practical context of social research, and introduces a new approach - adaptive theory - which can be used to generate new theory as well as develop existing theory in conjunction with empirical research. Layder concludes by providing an outline of new rules of sociological method that show how adaptive theory can be put into practice.