Research suggests higher parent expectations can predict more independent outcomes of youth with autism spectrum disorder (ASD), yet little is known about how parents' expectations are formed. To gain an understanding of their formation, we conducted semi-structured interviews with seven parents of adolescents with ASD. Three main types of influences on parent expectations were identified: factors related to the youth, to the parent, and to social and societal forces external to the family. Although not directly probed, all of the participants also discussed their approaches to planning for the future, suggesting a connection with their expectations. These findings contribute to a growing body of literature on the role of parent expectations during the transition to adulthood. Future research and clinical practice implications include designing interventions aimed at expanding parent expectations in addition to approaches directly preparing youth with ASD for adulthood as a means to improve outcomes.