The science of learning and development demonstrates the value of positive relationships for student success and well-being. This brief describes structures that secondary schools can integrate to cultivate conditions that enable healthy attachments to grow. Specifically, it highlights structures that can foster personal teacher--student relationships, including those that create small learning communities, promote safety and belonging, support culturally sustaining and relevant education, and foster student voice and agency. In addition, it describes structures that enable relationship-building between and among staff and families so that relationships can become more fully embedded into a school's culture and fabric. School structures can create opportunities for relationships to develop, but those structures are only as powerful as the interactions within them. Thus, this brief is a companion piece to the brief "Cultivating Relationships in Secondary Classrooms: Practices That Matter," which describes practices secondary-school staff can adopt to cultivate deep and affirming connections among individuals in their schools.