Diagnostic (mapping) and therapeutic (ablation, pacing) advances have provided insight into atrial depolarization processes and new developments in P wave analysis. Information about interatrial pathways is important to the understanding of interatrial conduction delay. A standardized method for P wave analysis is necessary for the development of a clinical role for management of patients with paroxysmal atrial fibrillation using signal-averaged P wave analysis and P wave dispersion. Algorithms for predicting localization of ectopic P waves may facilitate catheter ablation. P wave changes due to pacing at different atrial sites may be useful for permanent pacing for prevention of atrial fibrillation. Introduction of these developments into clinical practice should allow better prevention and treatment of atrial arrhythmias and could have considerable impact in view of their high frequency especially in the older population.