Museums' social resources, along with their status as places of informal learning, make them well-suited to serve people with autism spectrum disorder (ASD). As autistic young adults report high instances of social isolation and receive fewer services after high school, there is a clear need for more programing for this audience. In 2017, the San Diego Natural History Museum piloted SPECTRUM: Social Stories Project; the museum hosted 10 young adults with ASD who, in partnership, created pre-visit tools for other autistic museum visitors to Balboa Park. Supported with evaluation findings, including interviews with the young adults and museum professionals, and three naturalistic observations, we explore the reciprocal museum learning between program young adults with ASD and museum staff, who deepened their understanding of ASD because of social interaction in a museum setting.