© 2019, Springer Science+Business Media, LLC, part of Springer Nature. Acute pancreatitis (AP) is the most common gastrointestinal disease resulting in hospitalization in the United States with reports of over 270,000 hospitalizations and costs up to 2.6 billion dollars per year. AP is highly variable in disease course and outcome. Established in 1992, the original Atlanta classification system aimed to categorize the wide spectrum of AP by creating consensus-based terminology for AP types, severity, and complications. Though the original system standardized terminology, certain terms and definitions (i.e. pancreatic abscess) were unclear and often misused. The 2012 revised Atlanta classification (RAC) system updated terms, clarified definitions, and incorporated the medical community’s improved understanding of the physiology of AP. The resulting RAC effectively defined the morphologic types of pancreatitis, provided a more standardized system for disease severity grading, further classified the local retroperitoneal complications, and established objective measures to describe this highly variable but common disease. This review provides an update on the recent literature evaluating the RAC, discusses both the strengths and shortcomings of the RAC system (including problematic interobserver agreement), and considers improvements for future classification systems.