We examined barriers and facilitators to expanding primary care's capacity to manage conditions associated with autism spectrum disorder (ASD). We conducted semi-structured interviews with specialists, primary care providers (PCPs), primary care staff, and parents of children with ASD, discussing health/behavior problems encountered, co-management, and patient/family experience. Participants endorsed primary care as the right place for ASD-associated conditions. Specialists advising PCPs, in lieu of referrals, efficiently uses their expertise. PCPs' ability to manage ASD-associated conditions hinged on how behavioral aspects of ASD affected care delivery. Practices lacked ASD-specific policies but made individual-level accommodations and broader improvements benefitting children with ASD. Enhancing access to specialty expertise, particularly around ASD-associated behaviors, and building on current quality improvements appear important to expanding primary care.