This chapter introduces multiple theoretical contexts for understanding the impact of trauma. Building upon the foundational information presented in Chapter 1, the current chapter examines how the construct of trauma evolved from primarily life-span and psychological understandings, to a more systems and psychosocial perspective, to our current neurobiological realizations about the effects of trauma. The connections among facets of trauma, which are described in Chapters 1 and 2, offer a foundational scaffold upon which to understand the profound effects of traumatic experiences.