An employee benefit claim is decided by a private document under rules that most people discover only after their claim is denied, and by then the most important decisions have already been made. This article explains why the plan document controls, what the summary plan description is for, and why the internal appeal is not a preliminary step but the entire case. It sets out the deadline structure, the full and fair review requirements, and the reason the administrative record closes when the appeal does. It then explains the deference problem: how a discretionary clause changes the standard of review from ordinary contract interpretation to a demanding abuse-of-discretion standard, and how a structural conflict is weighed when the same entity pays and decides. Practical sections cover what a denial letter must contain, what to demand and submit on appeal, and the remedies actually available, including the frequent outcome of a remand rather than an award. Worked examples run throughout and every authority is linked.