This book is about the motivations of political actors. Many of the most commonly used models of party competition and government formation are grounded in explicit assumptions about the motivations of party strategists. These tend to assume one of three basic and interrelated motivations—the desire to fulfill policy objectives, the desire to control the perquisites of office, and the desire to maximize votes. While recognizing that living and breathing people may be driven by any or all of these motivations, among others, and that these may interact with each other in complex ways, most theorists ground their models in assumptions of policy-seeking OR office-seeking OR vote-maximizing by key political decision makers. Indeed this distinction between motivational assumptions is one of the most common ways to classify models of party competition. In part the grounding of models in a single motivational assumption is for the sake of analytical tractability; in part it is because the heuristic insights made possible by these approaches are enhanced if the models are kept simple and their relationship to core assumptions is kept straightforward.