PROJECT SUMMARY/ABSTRACT. Over 80% of adolescents with an alcohol use disorder (AUD) who present to treatment have a co-occurring psychiatric diagnosis. Although the best available treatments for adolescents with alcohol use disorders and co-occurring disorders (AUD+CODs) yield only modest short-term benefits, parent-involved treatments result in the best outcomes. In line with NIAAA’s strategic plan to improve treatments for AUD+CODs, this application seeks to address a central, yet unanswered question – what parenting behaviors during parent-involved treatment for AUD+CODs contribute to improved outcomes? Parenting is dynamic and varies from moment to moment depending on context, affect, and adolescent behavior. Moreover, treatment motivation, alcohol craving, alcohol and cannabis use, and internalizing and externalizing symptoms — core adolescent AUD+CODs treatment targets — vary considerably within and across days. Understanding the parenting behaviors during treatment that account for improved treatment outcomes requires momentary assessments that can capture the dynamic nature of parenting and core adolescent treatment targets. This K99/R00 study intends to leverage an experimental medicine framework to study how parenting, captured in real time in daily life, impacts core treatment targets (treatment motivation, alcohol craving, alcohol, and cannabis use, and internalizing and externalizing symptoms) among adolescents enrolled in an intensive outpatient for AUD+CODs. The specific aims for the K99 are to adapt parental communication, general parenting practices, and alcohol-specific parenting measures to EMA (Aim 1), conduct a pilot feasibility and acceptability study of the EMA protocol (N=20 parent-adolescent dyads; Aim 2a), and use mixed methods to evaluate and refine the EMA parenting measures and protocol (Aim 2b). Dr. Samuel Meisel’s overarching training goals are to (1) refine skills in independently designing, developing, and executing EMA research (Drs. Robert Miranda and Elizabeth McQuaid), (2) solidify expertise in conducting treatment research with adolescents with AUD+CODs (Drs. Aaron Hogue and Robert Miranda), (3) apply experimental medicine methods to adolescent AUD+COD treatment mechanisms research (Dr. John Kelly), and (4) promote a successful transition to independent faculty researcher. These training objectives build on Dr. Meisel’s F32 (AA028414), which provided him with the foundational training to broaden his research from studying the initiation and escalation of adolescent alcohol use to adolescent alcohol use treatment and mechanisms of behavior change. R00 specific aims include examining momentary parenting-core treatment target associations (N=75 parent-adolescent dyads; Aim 3a) and examining changes in the strength of parenting-treatment target associations over the course of AUD+COD treatment (Aim 3b). Findings will systematically identify the specific parenting practices during AUD+CODs treatment that most str...