The Advocacy Coalition Framework (ACF) remains one of the most established and applied approaches to studying policy processes. This chapter provides an overview of the ACF, including its assumptions and theories of advocacy coalitions, policy-oriented learning, and policy change. In doing so, it summarizes what is known about the policy processes under this approach based on the empirical applications that span the globe on various topics and using diverse methods. The chapter ends by identifying emerging areas ripe for continued development and offering advice to people interested in contributing to the ACF's research program.