Parenting self-efficacy (PSE) is a mother’s belief in her ability to raise a child. High PSE has been shown to be associated with several emotional benefits for the mother and child, including fewer depression symptoms, better adjustment to the parenting role, and less use of coercive discipline. Because of these beneficial outcomes, it is crucial to investigate factors associated with high PSE. The present study was particularly interested in factors that are associated with and influence PSE in first-time mothers of infants. First-time mothers experience a unique transition period that requires delicate care for their own postpartum health, while also caring for the multifaceted needs of a newborn. Based on the published parenting literature, we identified social support, prior experience with children, knowledge of child development, child temperament, mood, and mastery experiences as potential correlates and determinants of PSE. We examined PSE with two measures in order to assess both task-specific and domain-general PSE. A sample of 30 mothers with infants ranging from 4 to 12 months of age completed questionnaires online and also participated in a lab visit. During the lab visit, mothers participated in an established mood manipulation to examine how sad mood affects PSE and a novel mastery experience that involved recalling and writing about a time when they had successfully handled a challenging parenting task. Pearson’s correlations were conducted to test associations with both PSE scores. Paired t-tests were conducted to analyze changes in PSE after the sad mood induction and after the mastery experience. In line with our predictions, we found that greater self-reported infant surgency was significantly associated with higher task-specific PSE scores. Other correlations were in the predicted direction but were small and not statistically significant: association between greater social support, more prior experience with children, and greater surgency were positively correlated with domain-general PSE. The results from the lab visit revealed that mothers’ PSE was significantly lower after the sad mood induction, as well as after the mastery experience. The results of this study extend the current literature on factors associated with PSE in first-time mothers of infants. These findings can also readily be implemented in interventions aimed to increase parenting confidence in new mothers.