The chapter develops a theoretical framework for the study of representation, transforming the abstract concept of representation into a concrete, empirically measurable phenomenon. It introduces a new, multi-stage process model that captures the entire process of selecting problems and solutions, setting the agenda, discussing, bargaining, and decision-making. This model divides the representation process into four distinct stages: preference exchange, supply selection, preference expression, and policy selection. Since not all preferences held by citizens can be reflected in policy output, each stages plays a specific role in selecting which preferences will ultimately find representation. The chapter provides a detailed description of the exact function each stage fulfils in this selection process. At two stages of the process—preference exchange and preference expression—the main goal is to represent a diversity of preferences. At the two other stages—supply selection and policy selection—the main goal is to select popular preferences.