The Recruitment and Clinical Assessment Core (RAC) will be responsible for a) enrollment of participants; b) review and/or conduct of diagnostic, clinical, cognitive and behavioral assessments; c) systematic sequential scheduling of participants across Project 1 and 2; and d) data scoring, entry, tracking, QC procedures and data transfer procedures to the Data Management and Analytic Core (DMAC). The RAC interacts with the Administrative Core (AC) and the DMAC at all levels. The Objectives of the RAC are: Objective 1. Enrollment of 180 ASD patients and 100 controls for participation in the ACE, to ensure a core sample of 150 ASD and 75 control participants in Project 1, and 78 ASD participants in Project 2 (Project 2 will not enroll healthy controls). The RAC will be responsible for contacting, enrollment, and consenting of all participants; scheduling and clinical review of the physical examination and the cognitive and behavioral assessments; and the scheduling of the participants for assessments in Project 1 and 2. Objective 2. Characterization and Clinical, Medical, Cognitive and Behavioral Assessment of participation in the ACE. The RAC will a) obtain a thorough medical history of the participant and the family; b) conduct a physical examination; c) obtain questionnaires from parents/caregivers of all participants (ASD and Control), including: ACE Subject Medical History; ACE Family Medical History; Sleep Habits Questionnaire Child; Sleep Habits Questionnaire Parents; Social Responsiveness Scale (SRS-2): Stanford Social Dimension Scale (SSDS); Repetitive Behavior Scale, Revised (RBS-R); Dimensional Assessment of Restricted/Repetitive Behaviors (DARB); Sensory Profile Questionnaire (SPQ-2); Child Behavior Checklist (CBCL); Aberrant Behavior Checklist (ABC); and Vineland Adaptive Behavioral Scale, Third Edition (VABS-3); d) administer the Stanford Binet 5 or the Mullen Scales of Early Learning as appropriate, and the NEPSY-2 Affect Recognition subtest to all participants (ASD and controls); e) administer the Autism Diagnostic Interview-Revised (ADI-R) to parents of the ASD participants; f) administer the Autism Diagnostic Observation Schedule (ADOS-2) to the ASD subjects; and g) obtain the Social Communication Questionnaire (SCQ) from parents/caregivers of control participants. Objective 3. Acquisition, data entry, management and transfer to the Data Management and Analytic Core (DMAC) of all RAC demographic, medical, diagnostic, clinical, behavioral and cognitive data.