Young people transitioning from the foster care system have elevated risk for a range of mental health diagnoses that for many are exacerbated by psychosocial coping difficulties, sparse support networks, and service disengagement. This population is less prepared to cope with mental health challenges and more likely to have negative perspectives on help- seeking, increasing the risk of unmet treatment needs as service use rapidly declines following the exit from foster care. Our long-term goal is to deploy a scalable secondary prevention program that leverages existing foster youth transition services to improve mental health functioning and service use before and after exiting foster care. Our short-term objective is to remotely test a group intervention called Stronger Youth Networks and Coping (SYNC) that targets cognitive schemas influencing stress responses, including mental health help-seeking and service engagement, among foster youth with behavioral health risk. SYNC aims to increase youth capacity to appraise stress and regulate emotional responses, to flexibly select adaptive coping strategies, and to promote informal and formal help-seeking as an effective coping strategy. SYNC results from intervention development to design a novel program using evidence- based cognitive change methods, including adapting the Coping Effectiveness Training (CET) curriculum for foster youth. SYNC is designed for delivery by service providers in federally-funded Independent Living Programs (ILPs) accessed by most foster youth in the US. Initial feedback from foster youth, service providers, and our advisory panel confirmed the acceptability of SYNC curriculum topics (e.g., stress and coping, navigating services) and program strategy (e.g., groups co-facilitated by "near-peer" young adults with foster care and mental health care experience). The proposed aims will establish whether the 10-module program engages the targeted proximal mechanisms with a signal of efficacy on clinically-relevant outcomes, and whether a fully-powered RCT of SYNC is feasible in the intended service context. Our first specific aim is to refine our SYNC curriculum and training materials, prior to testing SYNC in a remote single-arm trial with two cohorts of 8-10 Oregon foster youth aged 16-20 (N=16). Our second aim is to conduct a remote two-arm individually-randomized group treatment trial with Oregon foster youth aged 16-20 with indicated behavioral health risk (N=80) to examine: (a) intervention group change on proximal mechanisms of coping self-efficacy and help-seeking attitudes, compared to services-as-usual at post-intervention and 6-month follow-up: and (b) association between the mechanisms and targeted outcomes, including emotional regulation, coping behaviors, mental health service use, and symptoms of depression, anxiety, and PTSD. Our third aim is to refine and standardize the intervention and research protocol for an effectiveness trial, including confirming transferability with national stakeholders. The demonstration of target engagement with initial evidence of efficacy, plus standardized intervention materials and a feasible research protocol, will prepare us for an effectiveness trial (R01) of a model that is expected to be widely transferable for implementation across the country, and one that can ultimately be adapted for other youth service settings (e.g., juvenile justice) and subgroups (e.g., lesbian, gay, bisexual, transgender, queer \[LGBTQ\], youth of color), expanding long-term public health impact.