This prospective study applies family stress theory to the influence of personal, child, and familial factors on a mother's parenting stress during the first 3 years of her infant's life. Participants included 134 mothers and their infants at ages 1, 6, 15, 24, and 36 months from one site of a multisite, longitudinal study. Mother's personality was most predictive of parenting stress cross-sectionally and longitudinally. Intimacy with partner reduced parenting stress early in the infant's life and at 36 months, whereas general social support was more important in the second year. Child temperament was influential at 1 and 36 months. Counterintuitively, mothers who were more satisfied with work or school choices were more likely to be chronically stressed. Implications are discussed.