RATIONALE: Early Life Stress (ELS) increases risk for both adult traumatization and posttraumatic stress disorder (PTSD). Adult PTSD may also reflect a continuation of a response to an earlier exposure to adversity. Given similarities between neuroendocrine aspects of PTSD and ELS, such as in reduced cortisol signaling and glucocorticoid receptor (GR) responsiveness, some aspects of the biology of PTSD may reflect biological correlates of risk. OBJECTIVES: This paper will examine how empirical findings regarding the biological basis of ELS can inform our understanding of the neuroendocrinology of PTSD. This paper will also propose a hypothetical model to guide future research that integrates genetic, epigenetic, neuroendocrine, and psychological observations to understand the contribution of ELS neurobiology to PTSD. RESULTS: Recent genetic findings demonstrate heritable aspects of at least some of these cortisol-related disturbances. Furthermore, ELS may produce at least some of the PTSD-associated changes in glucocorticoid responsiveness through epigenetic mechanisms such as developmental programming. These, then, may contribute to enduring changes in stress responsiveness as well as enhanced risk for adult exposure and PTSD. CONCLUSION: Molecular mechanisms associated with gene x environment interactions or GR programming are essential in explaining current observations in the neuroendocrinology of PTSD that have been difficult to understand through the lens of contemporary stress theory.