Parenting stress has been shown to affect relationships between mothers and their infants. Single mothers may experience more parenting stress due to exposure to stressors that are unique to their environment. The purpose of this secondary analysis was to determine the differences between married and single first-time mothers on the Parenting Stress Index/Short Form (PSI/SF ). A convenience sample of 22 single and 52 married first-time mothers were recruited from postpartum units in two large metropolitan hospitals in the southeastern United States. During hospitalization, participants completed a demographic sheet and at six weeks postpartum, were mailed the PSI/SF. T-tests were assessed for differences between mean scores. Study findings indicate significant differences between single and married first-time mothers on the Parental Distress subscale (t = −3.468, p = .001), the Difficult Child subscale (t = −2.032, p = .046), and Defensive Responding subscale (t = −3.720, p = .000), with single mothers consistently scoring higher than married mothers; however, there was not a significant statistical difference between mothers on the Parent-Child Dysfunctional Interaction subscale (t = −1.290, p = .201). Overall, single mothers scored higher on the Total Parenting Stress scores of the PSI/SF than married mothers (t = −2.858, p = .005), suggesting that single women experience more stress as a new mother than married new mothers. It is important to understand the specific stressors of new, single mothers and to develop nursing interventions that decrease parenting stress in single mothers.