Maternal Mentalizing as Protective Factor Against Racism-Related Trauma and Maternal Substance Use - Abstract Maternal substance use (SU) is a significant and growing public health problem. In 2020, over 26 million U.S. women used illicit substances, and SU rates among women giving birth have nearly quadrupled in the last decade. Despite these realties, mothers with substance use disorders (SUDs) remain an underserved and understudied population. For Black mothers in the U.S., the lack of research on risk, protective factors, and effective elements of treatment for maternal SU is even more pronounced. For example, while a growing body of research demonstrates the negative effects of racism-related trauma on a wide-range of health outcomes, no quantitative studies, and only a handful of qualitative studies have examined the contributions of racism- related trauma to maternal SU outcomes in Black women. For Black U.S. mothers, their own experiences of racism-related trauma, and the parenting stress they can experience in worrying about and processing their children’s experiences with racism, likely significantly impact feelings of fear, helplessness, parenting competence, and parenting stress which can all contribute to maternal SU risk. While racism-related trauma likely contributes to Black mother’s SU risk, in part through amplifying parenting stress, the parenting role, and particularly the quality of mother-child relationships, may also serve as a critical SU protective factor. One factor that has been shown to bolster the quality of the parent-child relationship and improve maternal SU outcomes is maternal mentalizing, defined as the capacity and tendency for mothers to observe and make generally accurate inferences about thoughts, emotions and intentions of themselves and others, including their child, and how they affect behavior. Recent maternal SU intervention studies show that improving maternal mentalizing improved mother-child relationship quality, buffered against the effects of other/non- racism related trauma on SU, and improved SUD recovery outcomes. Thus, mentalizing is likely an important protective factor for maternal SU outcomes, but no studies have investigated if maternal mentalizing may serve as a protective factor against the effects of racism-related trauma for Black mothers struggling with SUDs. The objective of the proposed study is to collect and analyze cross-sectional and longitudinal data on experiences of racism-related trauma and maternal mentalizing in a unique sample of Black mothers with SUDs who are seeking treatment at Drexel University College of Medicine’s Caring Together Program (>80% of patients identify as Black/AA; 85% are mothers of dependent children). This research will contribute to NIDA’s research priorities to: 1) better understand the real-world complexities and the impact of important social factors on maternal SUDs; and 2) conduct research that will significantly impact the promotion of health equality in SU research and practice. Accomplishing the study aims will provide important data on SUD risk and protective factors for Black/AA mothers and be a first step towards a future RO1 submission aimed at developing culturally responsive evidence-based assessment tools and intervention strategies.