This study examines the impact of the Special Olympics Unified Champion Schools program in high schools across the country. Data were analyzed from 2,774 students from 11 high schools implementing the program concerning their perceptions and attitudes toward including students with intellectual disability (ID). Students participating in 1 or more program activities reported increased visibility of and social interactions with students with ID in school. This, in turn, promoted more positive perceptions and attitudes regarding school and classroom inclusion. Participation in different activities had unique effects on students' perceptions of their school's inclusive environment and on their attitudes toward classroom inclusion. These findings support an ecological approach to social inclusion and for structured, schoolwide interventions embedded within normative school contexts.