Indigenous Peoples of the Americas have experienced devastating collective, intergenerational massive group trauma and compounding discrimination, racism, and oppression. There is increasing evidence of emotional responses to collective trauma and losses among Indigenous Peoples, which may help to inform ways of alleviating psychological suffering and unresolved grief. Tribal cultural and regional differences exist which may impact how the wounding across generations and within an individual's lifespan are experienced and addressed. This article will review the conceptual framework of historical trauma, current efforts to measure the impact of historical trauma upon emotional distress, and research as well as clinical innovations aimed at addressing historical trauma among American Indians/Alaska Natives and other Indigenous Peoples of the Americas. We will discuss assessment of historical trauma and implications for research and clinical as well as community interventions, and conclude with recommendations.

pervasive trauma exposure, collective histories of communal suffering, and elevated risk for depression and posttraumatic stress disorder. In addition to socioeconomic barriers, access to culturally responsive treatment is limited, which may compromise treatment engagement. The Iwankapiya study piloted the Historical Trauma and Unresolved Grief Intervention (HTUG), combined with Group Interpersonal Psychotherapy (IPT), to reduce symptoms of depression and related trauma and grief. The study hypothesized that HTUG ϩ IPT would lead to greater group engagement and decreased depression and related symptoms compared with IPT-Only. American Indian adults (n ϭ 52) were randomized into one of two 12-session interventions, HTUG ϩ IPT or IPT-Only, at two tribal sites: one Northern Plains reservation (n ϭ 26) and one Southwest urban clinic (n ϭ 26). Standardized measures assessed depression, posttraumatic stress disorder, grief, trauma, and substance use. Data were collected at screening, baseline, end of intervention, and 8 weeks postintervention; depression and group engagement measures were also collected at Weeks 4 and 8 of the intervention. Depression scores significantly decreased for both treatments, but there were no significant differences in depression between the two groups: IPT-Only (30.2 Ϯ 6.4 at baseline to 16.7 Ϯ 12.1 at follow-up) and HTUG ϩ IPT (30.2 Ϯ 8.1 at baseline to 19.9 Ϯ 8.8 at follow-up). However, HTUG ϩ IPT participants demonstrated significantly greater group engagement. Postintervention, clinicians expressed preference for HTUG ϩ IPT based upon qualitative observations of greater perceived gains among participants. Given the degree of trauma exposure in tribal communities, these findings in a relatively small sample suggest HTUG should be further examined in context of treatment engagement. Clinical Impact StatementQuestion: Does the Historical Trauma and Unresolved Grief Intervention (HTUG) combined with Group Interpersonal Psychotherapy (IPT) result in lower depression and increased treatment engagement than IPT alone? Findings: The Iwankapiya study suggests that American Indian adults with trauma histories are more engaged when therapy includes an emphasis on collective trauma and cultural values and practices, as in the HTUG component; depression scores decreased comparably for both treatment conditions groups. Meaning: Integrating the cultural and historical context increases treatment engagement, contributing to greater capacity for treatment gains such as reducing depression, trauma, and related symptoms. Next Steps: Given the degree of trauma exposure in tribal communities, these findings suggest HTUG should be further examined in a larger group in the context of minimizing barriers to treatment and examining the influence of treatment engagement.