The health care needs of individuals with autism spectrum disorder (ASD) are complex and multifaceted, with access to quality care a major challenge. Co-occurring physical and mental health conditions are highly prevalent in transition-age youth (TAY) and adults with ASD. Treating these conditions represents an important avenue for improving quality of life in this population. Provider-based training programs, such as Project Extension for Community Health Care Outcomes (Project ECHO), has been shown to increase provider knowledge self-efficacy, although their impact on health care outcomes and health care utilization in TAY/adults with ASD is understudied. The overarching goal of this K18 application is to provide training in health services research related to TAY/adults with ASD, specifically focused on harnessing data from electronic health records (EHR) to study health outcomes in future interventional studies. These skills are preparatory to designing and carrying out a rigorous future trial of Project ECHO is TAY/adults with ASD. In the K18, I will use deidentified datasets at Vanderbilt University Medical Center (VUMC) and Kaiser-Permanente Northern California (KPNC). My research specific aims are (1) Determine the utility of applying novel algorithms for identifying and characterizing cases of TAY/adults with ASD within the VUMC deidentified EHR and (2) Analyze how common physical and mental health conditions and measures of health care utilization change with increasing age in in an existing longitudinal cohort of TAY/adults with ASD within the KPNC EHR. My training goals are (1) Learn how to use pragmatic tools, such as natural language processing and phecodes, to identify TAY/adults with ASD and co-occurring conditions and (2) Learn how to analyze longitudinal health data. I will obtain this training through mentorship provided by Dr. Lisa Croen of KPNC and Drs. Jeffrey Neul and Lea Davis of VUMC as I conduct my research project. Formal coursework in Bioinformatics and Epidemiology, along with Responsible Conduct of Research, will enhance my practical experience. The environment provided by VUMC and KPNC is ideal for this training, given the expertise of both institutions in cutting-edge EHR-related research. The project is innovative given the proposed use of novel tools for identification and characterization of TAY/adults with ASD, and the proposed analysis of longitudinal EHR data related to health conditions and health care utilization.