Adoption provides a unique opportunity to study the simultaneous effect on adoptees’ development of environmental influences related to adoptive parenting, and children’s biology-based characteristics. In this paper, two Hybrid Dyadic Models were tested to study the mediational role of the adoptees’ negative reactivity on the relationship between mothers and fathers’ supportive (Model A) and unsupportive (Model B) parenting, and adoptees’ social skills. In a sample of 102 couples, mothers and fathers’ reports on adoptees’ social skills, the adoptees’ negative reactivity, and supportive/unsupportive parenting were explored. Supportive/unsupportive parenting was assessed individually (mothers and fathers separately), whereas the adoptees’ negative reactivity and social skills were treated as common fate variables, with both parents’ scores as indicators of a latent construct. Results were non-significant for Model A. Regarding Model B, different relation patterns between unsupportive parenting and social skills were found, depending on whether it was the mother's or the father's parenting. The child's negative reactivity mediated the relationship between the father's (not the mother's) unsupportive parenting and the child's social skills. With information from both parents and considering simultaneously their unique and shared perspectives, this study advances adoption research and strengthens the relevance of dyadic analyses when studying the adoptive family dynamics.