This chapter provides an overview of one framework that can help answer the questions: the Advocacy Coalition Framework (ACF). It begins with a summary of the intellectual foundations of the ACF. The ACF was created in the early 1980s by Paul Sabatier and Hank Jenkins-Smith. The foundations of the ACF were also influenced by debates in the philosophy of sciences that were still prominent in the 1970s and 1980s. Borrowing from Easton, Laudan, Lakatos, and Ostrom, the ACF is best thought of as a framework supporting multiple, overlapping theoretical foci. The traditional scope of the ACF includes questions involving coalitions, learning, and policy change. As suggested by the assumptions above, the framework is most useful for understanding these topics in high-conflict situations at the subsystem level of analysis. The chapter ends by suggesting an ongoing agenda to continue the advancement of the ACF research program.