The diagnostic criteria for autism spectrum disorder in the DSM-5-TR features the option to designate levels of support for social communication (SC) and restricted, repetitive behaviors (RRB). These levels are conceptual in nature, but research indicates standardized assessment outcomes correspond with clinician-assigned levels of support. The purpose of the present study was to identify factors that influence designated levels of support for SC and RRBs when diagnosing autism. Standardized assessment scores across intellectual functioning, adaptive skills, and ASD symptomology were analyzed to determine corresponding levels of support in SC and RRBs assigned by clinicians for 136 autistic children following a comprehensive diagnostic evaluation. At diagnosis, approximately 46% of participants were described as needing substantial support (Level 2) for SC and 49% were described as needing substantial support (Level 2) for RRB. There was a consistent pattern of higher to lower intellectual and adaptive functioning needing Level 1-Level 3 support. Autism assessment results followed a gradient of fewer to greater autism symptoms from Level 1 to Level 3 support. Findings indicated clinician-assigned levels of support for SC and RRB were associated with intellectual functioning, adaptive functioning, autism symptomology, and age, but not sex.