The authors examined the hypothesized influence of maternal and paternal hostility on youth delinquency over time. The investigation addressed significant gaps in earlier research on parental hostility, including the neglect of father effects, especially in African American families. Using prospective, longitudinal data from community samples of European American (n = 422) and African American (n = 272) 2-parent families, the authors examined the independent effects of paternal and maternal hostility on youth delinquency. The results indicated that paternal hostility significantly predicted relative increases in youth delinquent behaviors above and beyond the effects of maternal hostility; conversely, maternal hostility did not predict youth delinquency after controlling for paternal hostility. Multiple-group analyses yielded similar results for both ethnic groups and for boys and girls. These results underscore the importance of including both parents in research on diverse families. Neglecting fathers provides an incomplete account of parenting in relation to youth development.