ABSTRACT Children whose parents have substance use disorders (SUDs) or histories of incarceration are especially vulnerable to developing problematic substance use and disorders. These youth are also more likely to struggle with comorbid mental health disorders and engage in antisocial behaviors. Although mental health and substance use services can improve outcomes, youth face many barriers to receiving them. This is the first prospective, longitudinal study of intergenerational patterns of service use in high-risk families. I will investigate how parents’ experiences–their history of SUDs, service use, and barriers to services–affect their decision to seek services for their children. Data are from two studies: the Northwestern Juvenile Project, a prospective, longitudinal study of mental health needs and outcomes of 1829 youth in the justice system; and Next Generation, which interviews the original participants of the Northwestern Juvenile Project, and their children, ages 10-18 years (anticipated sample, n=640 parent and child interviews). All data collection will be completed by April 2023. Aim 1: What determines whether children who need services receive them? I will examine how demographic variables (e.g., age, sex, race, ethnicity) and clinical variables (type of drug used and comorbid mental health disorders) affect children’s service use. I anticipate that Black or Latinx youth will be less likely to receive needed services than non-Hispanic White youth; that the type of substance used will determine if youth receive services; and that youth with comorbid disorders (e.g., posttraumatic stress disorder) will be more likely to receive services. Aim 2: How do parents’ experiences with SUDs and service use—during adolescence and adulthood—affect their decision to seek services for their children? I will focus on parents’ history of SUDs, service use, attitudes, and barriers to service use during their own adolescence and adulthood. I anticipate that the timing of the parents’ SUDs (only during their own adolescence vs during their child’s lifetime) and the location of the parent’s services (community vs corrections) will affect the children’s service use. I hypothesize that parents who experienced barriers to receiving services during adolescence are less likely to seek services for their children than those who did not. My findings will provide the empirical basis for future studies to identify novel strategies to reduce barriers to services and to engage high-risk youth in services. My training will be strengthened by the mentorship of Dr. Linda Teplin, the Principal Investigator of the Northwestern Juvenile Project and Next Generation, her collaborators, Drs. Karen Abram and Leah Welty, and key personnel, Drs. Margareta Alegria and Faye Taxman, experts in health inequities in service utilization. The proposed fellowship training plan will prepare me to become an independent researcher of addiction science, focusing on health inequities ...