This study investigated the influence of infants’ sleep and crying on marital relationship in first-time parent couples (N = 107) during the 1st year after birth. Control variables are parents’ insomnia and parental self-efficacy in handling the baby. Questionnaires were administered to both parents before birth, at 2 and 7 weeks after birth, and at 1 year after birth. Results show that marital problem-solving ability did not change but that marital satisfaction diminished significantly over time. Crying was the main child variable that affected marital satisfaction. Fathers’ self-efficacy contributed positively to marital problem solving and negatively to paternal insomnia. Both maternal and paternal insomnia affected spouses’ insomnia. As infant sleep problems may worsen preexisting parental insomnia, it is recommended that first-time parents be informed about treatments of insomnia. (Author abstract).