The impact of peer microaggressions and the child–teacher relationship on the social skills of children with sexual minority parents has received little attention. The current study used a mixed-method, multi-informant, two-wave longitudinal design to address this research gap. Thirty-seven children of lesbian mothers through donor insemination and 33 children of gay fathers though surrogacy (wave 1: Mage = 8.3 years, SD = 1.6; 51.4% female; wave 2: Mage = 9.9 years, SD = 1.7), all school-aged and residing in Italy, participated together with their 140 parents and 55 teachers. Approximately two-thirds of the children reported at least one peer microaggression and, on average, microaggressions were of a low intensity. Child–teacher relationships were of high quality (i.e., characterized by high safe haven–seeking and secure base use, and low conflict). Both parents and teachers reported high levels of child social skills. However, more intense W1 microaggressions predicted lower W2 social skills among children reporting a lower W1 child–teacher relationship quality, and greater W2 social skills among those reporting a higher W1 child–teacher relationship quality. These results support the child–teacher relationship as a potentially secure context in which children can “mentalize” negative experiences such as microaggressions and improve their social skills. In this vein, considering microaggression, attachment, and developmental intergroup theories, teachers must attune to the school experiences of children with sexual minority parents and cultivate caring classroom environments that are sensitive to family diversity.