Few fMRI studies have investigated the brain-behavioral basis of parenting in human fathers. Ten fathers were videotaped and gave salivary testosterone samples while interacting with their 2–4 months old infants, and viewed video clips of their own infant and an unfamiliar age-, ethnicity- and sex-matched other infant during an fMRI protocol. Infant stimuli activated a network of prefrontal and subcortical brain regions. Furthermore, a subset of these regions activated significantly more to own (OWN) than other (OTHER) infants. Finally, neural responses to OWN versus OTHER were linked with paternal sensitivity, paternal reciprocity, and testosterone. In sum, our results provide a novel perspective on the links between brain, behavior, and hormones in fathers.