The US Supreme Court will soon decide the fate of the Chevron doctrine. As the legal community awaits this ruling, there has been heightened attention on how courts review agency decision-making across multiple dimensions, even beyond Chevron deference. Our quick guide to agency deference provides a top-line summary of the key cases that inform judicial review of agency decisions—from agencies’ policy judgments to their interpretations of governing statutes and regulations. This guide can serve as a companion for understanding the upcoming Supreme Court decision and its implications for the road ahead for the administrative state.