This paper describes a proposed model of diagnostic evaluation for autism spectrum disorder (ASD) at a large-scale ASD specialty center. Our center has implemented age-based diagnostic tracks within an interdisciplinary team evaluation approach to assessing ASD. Data were collected as part of a program evaluation and included responses from provider surveys as well as patient medical record reviews. The results from 803 patients were included. The diagnostic outcomes, time for evaluation, and appropriateness of referral were analyzed in patients referred to the Younger (n = 155) and Older (n = 648) diagnostic tracks. In 92.8% of cases referred to the clinic’s standard team evaluation model, the provider teams were able to make a diagnostic decision within the allotted evaluation time. The results from an additional diagnostic pathway, termed the Autism Psych Team (APT), within the older track were also presented. The intake providers had the option to triage older patients to this pathway when they anticipated that the patient might be diagnostically complex. Most patients (45.1%) triaged to the APT were referred due to psychiatric complexity. In 96% of APT cases, the APT providers felt the patient was an appropriate referral. Overall, these results suggest a method to efficiently triage patients to diagnostic models equipped to serve them within a high-volume ASD center.