Young people living with HIV (YPLWH, 10-24 years of age) are a growing population that experience unique mental health challenges that may compromise their HIV care. Despite the clear need, few evidence-based mental health interventions exist to address the difficulties faced by this important population. The long-term goal of our research is to provide developmentally appropriate, evidence-based mental health interventions that effectively prevent and treat HIV in young people, especially in low resource settings where the majority of the epidemic occurs. Sauti ya Vijana (SYV, The Voice of Youth), is a novel and innovative group-based mental health and life skills intervention designed with and for Tanzanian YPLWH to address the mental health and life challenges they have described in our prior research. The intervention consists of 10 group sessions (two joint with caregivers) and two individual sessions delivered by trained young adults living with HIV who have successfully transitioned to the adult clinic using a task sharing model that builds local capacity while overcoming the critical shortage of mental health professionals in this setting. SYV incorporates components of Trauma Informed-Cognitive Behavioral Therapy, Interpersonal Psychotherapy, and Motivational Interviewing that during this critical neurodevelopmental period, when foundations of self and social regulation are realized, may prevent or dramatically reduce severity of mental health symptoms. The overall objectives of this proposal are to support positive coping strategies that bolster mental health and lead to improved HIV outcomes among YPLWH. The central hypothesis is that SYV will be effective to improve antiretroviral therapy (ART) adherence and virologic suppression in YPLWH in Tanzania. The rationale for this project is that by targeting mental health, which is strongly associated with medication adherence, we will effectively improve adherence and thereby HIV viral suppression. The central hypothesis will be tested in three aims in a hybrid type-1 effectiveness-implementation trial. The first aim will use an individually randomized group treatment trial design to determine if SYV is effective based on the primary outcome of 10% increase in virologic suppression (HIV RNA <400 copies/mL) among YPLWH in the intervention arm compared to standard of care. The second aim will elucidate the mechanisms by which SYV works and for whom it is most effective by evaluating potential moderators and mediators of the intervention using structure equation modelling. Change in mental health, internal stigma, resilience and coping are hypothesized to mediate the intervention effect, while age, sex, site, and baseline mental health symptoms are hypothesized moderators. The final aim will evaluate implementation determinants and outcomes, including cost effectiveness and sustainability guided by the Consolidated Framework for Implementation Research (CFIR) to identify any implementation di...