As rates of autism spectrum disorder (ASD) increase, there is an increasing need for clinicians who offer accurate ASD assessments. The Autism Diagnostic Observation Schedule, Second Edition (ADOS-2) is a standardized assessment tool that is commonly recommended for use in comprehensive ASD evaluations. However, practitioners do not always follow protocols established by assessment developers. Due to difficulty administering the ADOS-2, limited access to training for practitioners, and the complexity of ASD symptom presentation, false diagnoses of ASD are common, creating barriers to appropriate services. The present study explores the standardized use of the ADOS-2 across treatment settings. School and community practitioners involved in ASD assessment were surveyed on their use of the ADOS-2. Participants (n = 268) included individuals working in an array of settings who performed ASD evaluations. Participant involvement in ASD evaluations, current work setting, types of ADOS-2 specific training received, and ADOS-2 module most often used, were explored. These characteristics were compared to use of the ADOS-2 and likelihood of administering each activity. Findings suggest barriers to the use of and training on the ADOS-2 for school-based practitioners compared to those in other settings. Neither setting nor level of ADOS-2 training impacted administration standardization of the measure for participants.