["Autism Research, EarlyView. ", "\nABSTRACT\nPerformance‐based assessments of sensory function provide essential insights into sensory integration challenges in autistic children and provide objective, standardized measurement data that can be used to tailor targeted interventions. We sought to evaluate the validity and reliability of data collected using the Evaluation in Ayres Sensory Integration (EASI) for assessing sensory and motor functions in autistic children. We used the Rasch Measurement Model to evaluate data collected with 146 autistic children aged 3–12 years (United States: n = 24, Australia: n = 115, Brazil: n = 7). We analyzed 19 performance‐based tests assessing sensory perception, praxis, and motor functions. Rasch analyses examined item fit, unidimensionality, item targeting, and internal reliability. Seventeen of 19 analyzed EASI tests demonstrated strong construct validity, with adequate item‐fit and unidimensionality. Fourteen tests met reliability thresholds (person separation reliability ≥ 0.70), while five tests exhibited lower person separation reliability. Some tests showed poor item targeting, potentially limiting their precision for children with stronger sensorimotor abilities. Most EASI tests demonstrate strong validity and reliability for assessing sensory integration in autistic children. Clinicians can use tests meeting reliability thresholds with confidence; tests with lower reliability can provide useful information but should be corroborated with other clinical data. Findings for PF should be considered preliminary given limited sample size. In general, this initial validation of EASI advances the evaluation of sensory integration for autistic children.\n"]