Atrial fibrillation is a chronic, progressive condition that presents a major health burden. This review summarizes recent studies assessing atrial fibrillation progression and its associated risk factors, describes the mechanisms underlying atrial fibrillation progression, and discusses the clinical implications of the progressive nature of atrial fibrillation. Progression of atrial fibrillation burden, and clinical progression from paroxysmal to more advanced (persistent/permanent) forms is common, but progression rates are variable. Atrial fibrillation progression parallels progressive atrial remodeling induced by atrial fibrillation risk factors and atrial fibrillation itself, and is associated with worse clinical outcomes.