Introductory chapters present the background of theory in PSM, providing a mapping of major types of theory to deliver guidance on appropriate theory application and when a new theory or mid-range theory development is required. Featuring more than 25 theories with relevance across management research, each chapter presents an excellent overview for beginning the exploration of a certain theory. The authors discuss assumptions about different theories such as agency theory, transaction cost, and game theory, and explore levels of analysis, unit of analysis, variables and relationships, as well as key research findings. In addition, chapters include lists of selected seminal literature for further reading. The Handbook will be a key reference for scholars in management and marketing fields, particularly empirical researchers in operations and management sciences.