Asthma exacerbations are a frequent reason for pediatric emergency medical services (EMS) encounters. The objective of this study was to examine the implementation of evidence-based treatments for pediatric asthma in a regional consortium of EMS agencies. This retrospective study applied the Reach, Effectiveness, Adoption, Implementation, and Maintenance (RE-AIM) implementation framework to data from an EMS agency consortium in the Cincinnati, Ohio region. The study analyzed one year before an oral systemic corticosteroid (OCS) option was added to the agencies’ protocol, and five years after the protocol change. We constructed logistic regression models for the primary outcome of Reach, defined as the proportion of pediatric asthma patients...