Since cases were first reported in 1994, catheter ablation of atrial fibrillation has undergone rapid development and expansion. The procedure began as an attempt to recreate the Maze III operation with a catheter technique. Understanding the contribution of the pulmonary veins to the initiation and maintenance of atrial fibrillation led to dramatic changes in procedural technique. The segmental ostial and the circumferential approaches have emerged as the 2 dominant methods. Efforts continue in academic centers to better understand the pathophysiology of the arrhythmia and to further refine the ablation procedure to improve patient outcomes.