The theory of historical trauma was developed to explain the current problems facing many Native Americans. This theory purports that some Native Americans are experiencing historical loss symptoms (e.g., depression, substance dependence, diabetes, dysfunctional parenting, unemployment) as result of the cross-generational transmission of trauma from historical losses (e.g., loss of population, land, and culture). However, there has been skepticism by mental health professionals about the validity of this concept. The purpose of this article is to systematically examine the theoretical underpinnings of historical trauma among Native Americans. The author seeks to add clarity to this theory to assist professional counselors in understanding how traumas that occurred decades ago continue to impact Native American clients today.Keywords: historical trauma, Native Americans, American Indian, historical losses, cross-generational trauma, historical loss symptomsCompared with all other racial groups, non-Hispanic Native American adults are at greater risk of experiencing feelings of psychological distress and more likely to have poorer overall physical and mental health and unmet medical and psychological needs (Barnes, Adams, & Powell-Griner, 2010). Suicide rates for Native American adults and youth are higher than the national average, with suicide being the second leading cause of death for Native Americans from 10-34 years of age (Centers for Disease Control and Prevention [CDC], 2007). Given that there are approximately 566 federally recognized tribes located in 35 states, and 60% of Native Americans in the United States reside in urban areas (Indian Health Services, 2009), there is much diversity within the Native American population. Therefore, it is difficult to make overall generalizations regarding this population (Gone, 2009), and it is important to not stereotype all Native American people. Still, Native American individuals are reported as having the lowest income, least education, and highest poverty level of any group-minority or majority-in the United States (Denny, Holtzman, Goins, & Croft, 2005) and the lowest life expectancy of any other population in the United States (CDC, 2010).To explain why some Native American individuals are subjected to substantial difficulties, Brave Heart and Debruyn (1998) utilized the literature on Jewish Holocaust survivors and their decedents and pioneered the concept of historical trauma. The current problems facing the Native American people may be the result of a legacy of chronic trauma and unresolved grief across enacted on them by the European dominant culture (Brave Heart & DeBruyn, 1998, p. 60). The primary feature of historical trauma is that the trauma is transferred to subsequent generations through biological, psychological, environmental, and social means, resulting in cross-generational cycle of trauma (Sotero, 2006). The theory of historical trauma has been considered clinically applicable to Native American individuals by counselors, psychologists, and psychiatrists (Brave Heart, Chase, Elkins, & Altschul, 2011; Goodkind, LaNoue, Lee, Freeland, & Freund, 2012; Myhra, 2011). However, there has been uncertainty about the validity of this theory due to the ambiguity of some of the concepts with little empirical evidence (Evans-Campbell, 2008; Gone, 2009). Specifically, there has been lack of research about how the past atrocities suffered by the Native American people are connected with the current problems in the Native American community. The intent of this article is to examine the theoretical framework of historical trauma and apply recent research regarding the impact of trauma on an individual's physiological functioning and cross-generational transmission of trauma. Through this analysis, the author seeks to assist professional counselors in their clinical practice and future research.Core Concepts of Historical TraumaSotero (2006) provided conceptual framework of historical trauma that includes three successive phases. …