Clinical Core Abstract The purpose of the Clinical Core is 1): To manage recruitment activities and consent and enroll a Pittsburgh ACE Cohort for participation in the three Projects. We will prioritize increased participation by individuals traditionally minoritized in ASD research (e.g., race/ethnicity, LGBTQIA+, females, and diagnosis of ASD in adulthood); 2): Administer, score, and enter data for ASD diagnostic assessments and administer all RFA- required and center-wide phenotypic measures; 3) Apply a novel posterior probability of diagnosis (PPOD) index to estimate the presence of psychiatric diagnoses and ASD; 4) Establish age-related variables for use across Projects, including a biomarker of brain age and documentation of age of ASD diagnosis; 5) Manage scheduling of participants for all Projects. 6) Support retention of participants and monitor progress through Projects; 7) Monitor risks related to suicidality and other adverse events, and 8) To collaborate with other Cores and Projects. The Core will enroll 200 autistic and 100 non-autistic 18- to 65-year-old adults (>50 in each group with a recent history of suicidal ideation or behaviors [SI/SB], defined as active SI/SB within the past four months). We anticipate needing to consent and assess approximately 100 additional individuals to account for those who do not meet inclusion criteria. Those meeting study inclusion criteria will be invited to participate in all three Projects. Our team has consistently met recruitment goals for numerous NIH-funded studies of autistic adults, we have active partnerships with several registries for autistic and non-autistic adults, and we will collaborate with the Dissemination and Partnership Core to enhance our inclusion of autistic adults from groups that have been marginalized. The Clinical Core organizes the extensive recruitment effort to assure the Projects meet their targeted enrollments and complete their proposed studies, while assuring all the data mandated by the ACE funding mechanism is collected. The centralization of these services in a Core combines the recruitment resources that would otherwise be distributed across Projects, thereby reducing the redundancy and inefficiency that would occur if each Project had to perform these efforts individually. Research-reliable Clinical Core staff will conduct ASD diagnostic and cognitive assessments using the tools outlined in the RFA; this also creates an efficient process and supports the collaboration of investigators new to autism in this ACE center. Finally, Clinical Core staff are highly experienced in the assessment of SI/SB and psychiatric diagnoses and will monitor for suicide-related risks.