Receiving a diagnosis of autism for their child can be a pivotal moment for parents, yet there is little research about how providers can predict parent reactions and adjust their feedback. We investigated factors related to parent reactions during the disclosure session using interviews with providers (n = 6), a parent focus group (n = 10), and a mixed-methods survey of parents (n = 189) of recently diagnosed children. Parents’ prior knowledge of autism and anxiety about diagnosis predicted emotional reactions and readiness for next steps. Families anxious about receiving a diagnosis are most in need of information but may leave the session feeling lost and unprepared. Providers can promote positive emotional reactions for parents and prevent confusion by increasing their own positivity, warmth, respect, clarity, and confidence.