Fathers have an increasingly important role in the family and contribute through their sensitive responsiveness to positive child development. Research on parenting more often included fathers as caregivers in the past two decades. We present a neurobiological model of sensitive responsive parenting with a role for fathers' hormonal levels and neural connectivity and processing of infant signals. We tested this model in a research program (Father Trials) with correlational and randomized experimental studies, and we review the results of these studies. So far, interaction-focused behavioral interventions seem most promising in supporting fathers' sensitive respon-siveness, even though the mechanisms are still uncharted.