Preschool-aged siblings of children with ASD are at high-risk (HR) for ASD and related challenges, but little is known about their emerging peer competence and friendships. Parents are the main providers of peer-relationship opportunities during preschool. Understanding parental challenges supporting early peer relationships is needed for optimal peer competence and friendships in children with ASD. We describe differences in peer relationships among three groups of preschool-aged children (15 HR-ASD, 53 HR-NonASD, 40 low-risk, LR), and examine parent support activities at home and arranging community-based peer activities. Children with ASD demonstrated precursors to poor peer competence and friendship outcomes. Parents in the HR group showed resilience in many areas, but providing peer opportunities for preschool-age children with ASD demanded significant adaptations. [Article co-written with the Infant Brain Imaging Study (IBIS) Network.]