In California, individuals with autism and co-occurring mental disorders, and their families, face two serious barriers when attempting to access the mental health services they need. The first is that the State Mental Health Specialty Service guidelines specifically exclude autism as a qualifying primary diagnosis for eligibility for mental health treatment and funding. The second is the lack of understanding and awareness regarding the challenges faced by individuals with classic autism and co-occurring mental disorders and their families. These two barriers, combined with the absence of a clear protocol for referral and assessment, have made access to services for clients and their families difficult. The Adult Autism Spectrum Disorder and Co-Occurring Mental Health Disorders project was an opportunity to study potential assessment tools and referral guidelines. We evaluated the use in a clinical setting of the Schedule for the Assessment of Psychiatric Problems Associated with Autism--a research instrument designed specifically for the psychiatric evaluation of patients with autism--to assist in diagnosing co-occurring mental health disorders. The experience gained in this study helped identify effective treatment options as well. After the assessment, clients were offered choices among several possible treatments fitting their specific needs. Our experience indicates that while adapting a research tool to everyday clinical service may encourage a more rigorous standardized approach to clinical assessment and evaluation, it may be difficult to employ such a tool in a clinical setting because of service needs and managed care constraints of serving a large and diverse population.