Background: Schools are an ideal setting for implementation of asthma interventions for children; however, sustaining school-based programs can be challenging. This study illustrates policy and practice changes brought about through the Childhood Asthma Linkages in Missouri (CALM) program to sustain such programs. Methods: Researchers analyzed caregiver-reported quantitative data regarding asthma-related outcomes in preintervention and postintervention surveys and qualitative data regarding sustainability efforts in schools reported by CALM grantees. A grounded theory approach was used to identify key concepts and themes that emerged. Results: In 330 children, significant improvements were seen in asthma symptoms, rescue inhaler use, health care utilization, school absenteeism, and activity limitations. Overall, 27 school-based policy and practice changes supporting program sustainability were reported, with policy changes most often concerning the assessment and/or monitoring of children with asthma in the school setting, and practice changes most often regarding institution of regular asthma education programs for students and school personnel. Conclusions: Sustaining school-based asthma programs is challenging, but can be realized through the participation of diverse partners in enacting policy and practice changes that support the institutionalization of programs into the day-to-day processes of the schools.