The present study examined how a multicomponent intervention embedded in a high school's extracurricular framework impacts students' acceptance of peers with intellectual disability (ID). Data were collected from eight high schools, three of which implemented the Special Olympics Unified Champion Schools (UCS) program involving inclusive sports, clubs, and schoolwide events, and five of which did not. A pretest-posttest survey design was used to measure students' attitudes, perceptions, and interactions (n = 1,230). Lagged dependent variable modeling revealed that UCS participation significantly predicted improved attitudes toward peers with ID and perceptions of school social inclusion, as well as increased social interactions with peers with ID. Unified extracurricular activities may be the next step forward in promoting an inclusive school culture.