Students with autism spectrum disorders (ASDs) in Saudi Arabia are provided with the educational services they need in their local schools, but a standardized checklist is needed to measure the level of progress and the benefits acquired through the educational programs. This study aimed to standardize a version of Saudi performance norms on the Autism Treatment Evaluation Checklist (ATEC) to explain the raw scores that students with ASDs have obtained, using a sample of teachers and parents. The number of respondents in the study was 334 teachers, and 206 parents. Descriptive statistics, internal consistency, confirmatory factor analysis, reliability coefficients and percentiles were used for analyses. The study found that the ATEC had suitable indicators of validity and reliability, and the percentile ranks were extracted for interpreting the raw scores of the ATEC.