This study employed Rasch analyses to validate a novel measure of sport experience: the Sport Experience Measure: Children and Youth (SEM:CY). Analyses were applied to self-reported data of n = 503 young people (age 9–18 years, M = 12.91, 50% female) in Canada who were engaging in sport during the previous 12 months. The revised measure, consisting of 24 items on a 3-point response scale, demonstrated good fit statistics (e.g., item fit residual: M = −0.50, SD = 0.94 and person fit residual: M = −0.62, SD = 2.33), an ability to reliably discriminate between levels of sport experience, and an absence of differential item functioning for various groups (males and females, older and younger individuals, solo and team sports, and those playing at various competitive levels, including recreation). The SEM:CY is a succinct tool that can serve as a valuable means to gauge the quality of an individual’s sport experience, which can facilitate positive youth development and sustain participation across the life span.