Prolonged P-wave duration, a marker of left atrial abnormality, is associated with myocardial fibrosis, atrial fibrillation, and all-cause death. It is not known if prolonged P-wave duration is associated with sudden cardiac death (SCD) in the general population. We aimed to evaluate whether prolonged P-wave duration is independently associated with SCD risk in the Atherosclerosis Risk in Communities Study, a community-based prospective cohort study. We included 15,321 participants in our analysis (age 54.2 ± 5.7 years, 55.2% women, 26.4% black). Prolonged P-wave duration was defined as maximum P-wave duration >120 ms and was determined from 12-lead electrocardiograms obtained during 4 exams (1987 to 1999). SCD was physician adjudicated and defined as a sudden, pulseless condition in a previously stable patient without evidence for noncardiac cause of death. We used Cox proportional hazard models to assess the association between prolonged P-wave duration and SCD, adjusting for cardiovascular risk factors and conditions including atrial fibrillation. During a mean follow-up of 12.5 years (1987 to 2001), 268 SCDs were identified. The multivariable hazard ratio (95% confidence interval) of prolonged P-wave duration for SCD was 1.70 (1.31 to 2.20). This association was attenuated but remained significant after updating covariates to the end of follow-up with a hazard ratio of 1.35 (1.04 to 1.76). In conclusion, prolonged P-wave duration is independently associated with an increased risk of SCD in the general population. This association is independent of atrial fibrillation and is only partially mediated by shared cardiovascular risk factors.