Fathers in northern Utah and southern Idaho (N = 132), whose families were applicants for an Early Head Start (EHS) program, answered interview questions about their knowledge of infant development, their involvement with their own infants, their psychosocial functioning, and other background information. Because of the predominance of Mormon culture in this region, religious groups were compared. For Mormon and non-Mormon fathers, knowledge was related to feeling in control of their lives and involvement was related to feeling less depressed and using more community support resources. Mormon fathers' knowledge was related to spiritual support, religious activity, and education; their involvement was related to informal support, more ambivalence in close relationships, and fewer work hours. Non-Mormon fathers' knowledge was related to less depression and to less avoidance and ambivalence in close relationships; their involvement was related to feelings of control, spiritual support, and less avoidance in close relationships. Non-Mormon fathers who knew more about infants were also more involved with them, but surprisingly, Mormon fathers who were more knowledgeable were less involved with their infants. These differences in religious groups are discussed in relation to explicit and implicit messages about parental roles in Mormon theology and culture. © 1999 Michigan Association for Infant Mental Health