PROJECT SUMMARY/ABSTRACT. Obesity is a significant public health concern among all racial/ethnic groups, ages, gender, and geographic areas, but some groups are more disproportionately affected than others. Ethnic minority adolescents, especially AAs, are disproportionately likely to be obese relative to non-Hispanic White adolescents.29,30 The proposed study is designed to improve a comprehensive multicomponent family- based behavioral intervention (FIT Families) delivered by Community Health Workers (CHWs; therapists) for African American (AA) adolescents with obesity (AAAO). This application expands a program of research that has followed the Obesity Related Behavioral Intervention Trials (ORBIT) for developing behavioral treatments,31 by capitalizing on our recent work using innovative artificial intelligence technologies to thoroughly examine within-session therapy processes (i.e., mechanisms of action), specifically the role of CHW empathy in the development and maintenance of the therapeutic alliance (TA) while treating AAAO and their primary caregivers. TA is considered an essential element of therapy.32 The TA is composed of three features: 1. Emotional bond between therapist and client; 2. Agreement between the client and therapist on the goals of treatment; and 3. Agreement on the tasks of therapy.33 TA is a dynamic, bidirectional, and synergistic element of therapy with implications across differences in race, age, and gender of the client and therapist. Therapist empathy is critical in establishing and maintaining a strong TA, with outcomes mediated by the therapeutic alliance. Empathy accounts for more variance in therapy outcome than specific interventions34 and consistently predicts client change.35 Unfortunately, analysis of crucial facilitative interpersonal skills such as therapist empathy is technically challenging as the intent of another's behavior is nuanced, contextual (e.g., therapists and client differ in personality, background, cultural values, etc.), and interactive (bidirectional and synergistic); and can be expressed in multiple ways (voice tone, physiology]). To better understand empathy, requires empirical approaches and analytical tools that can discern empathetic behaviors in actual clinical encounters that produce behavior change. We will operationalize empathy through two measures that are each associated with empathy and treatment outcomes: 1) Empathic accuracy, defined as the CHW's accurate understanding of the client's state; and 2) Interpersonal physiological synchrony (IPS), defined as the correlation between therapist and client IPS over time (i.e., heart rate [HR], HR variability, galvanic skin response, voice features). This study uses these two empathy measures to understand the relationship between empathy, therapeutic alliance, and treatment outcomes. Further, the study will explore how empathy effects change based on the race and gender concordance/discordance of therapist-client dyads. Toward futu...