Universal autism screening is recommended by the American Academy of Pediatrics at 18 and 24 months. However, many children are not identified until after the age of 4 years, and some not until adulthood, either due to mild or no indication of symptoms early in development, or to co-occurring conditions which may overshadow autism symptoms. This indicates a need for universal autism screening measures for school-age children. This project adapts the widely used toddler autism screening tool, the Modified Checklist for Autism in Toddlers, Revised, with Follow-Up (M-CHAT-R/F), for use in school-age children, called M-CHAT-School (M-CHAT-S). The study follows the Patient-Reported Outcomes Measurement Information System guidelines for measure development to create parent- and teacher-report versions of the M-CHAT-S for 4- to 8-year-old children. Through expert consensus feedback via a Delphi pool and cognitive interviewing with stakeholders (i.e. parents and teachers), we developed two versions of the M-CHAT-S to be used for verbal and minimally verbal children. The M-CHAT-S poses several advantages to existing measures, including brevity, items updated based on current knowledge and conventions, and narrow age range to assure items are developmentally appropriate. Future steps include validation of the M-CHAT-S to determine its utility as an autism screener for young school-age children.