PROJECT SUMMARY/ABSTRACT Alcohol is one of the primary determinants of health disparity facing Indigenous populations today. Indigenous populations exhibit the highest rates of binge and heavy drinking, and lifetime (43.4%) and 12- month (19.2%) rates of alcohol use disorder are substantially higher than among other racial/ethnic groups. Further, Indigenous populations are significantly less likely to complete alcohol treatment; those that complete treatment are quicker to relapse and display more severe patterns of alcohol use. There is a paucity of empirically based interventions designed by and for Indigenous communities, which has led communities and research partners to rely on adaptations of existing empirically based interventions originally designed for non- Indigenous populations. Indigenous populations have increasingly advocated for health interventions to be culturally grounded. A culturally grounded approach involves close collaboration among communities and researchers in the design of intervention efforts rooted in Indigenous knowledge, protocols, and practices. This draws from cultural strengths, using Indigenous history, language, values, and healing traditions as a way for Indigenous populations to reclaim their cultural beliefs and practices. Research that applies a culturally grounded framework to address historical trauma in alcohol interventions is a critical next step to improving the health and well-being of Indigenous populations. Indigenous populations have faced histories of genocide, colonization, forced assimilation, and exclusion that undermine health and well-being. Historical trauma resulted in cultural shifts in alcohol use. Acts of oppression stemming from colonization such as the banning of traditional ways of healing left Indigenous people without mechanisms for coping with emotional distress. This coupled with the emotional aftereffects of historical trauma made Indigenous people vulnerable to developing maladaptive ways of coping. Indigenous populations began using alcohol as a way of self-medicating to escape or avoid traumatic memories and emotional pain associated with historical trauma. The objective of this project is to develop and obtain preliminary data on a culturally grounded, trauma- informed alcohol intervention. The specific aims are to (1) use Community-Based Participatory Research methods to deepen partnerships with Kingsclear First Nation through capacity-building and knowledge sharing; (2) collect and apply qualitative data to develop a culturally grounded, trauma-informed alcohol intervention that is focused on historical trauma for use with a First Nation sample; and (3) conduct a pilot RCT study to examine acceptability, sustainability, and initial efficacy data of the intervention compared to waitlist control. The research team (PIs: Spillane and Weiss; Co-I: Yang; Consultants: Gore and Moore) has expertise in the study content (e.g., alcohol use and historical trauma among Indigenous ...