Clinicians and researchers alike have realized that at the cutting edge of our understanding of stressful life events are a multiplicity of theories and means by which we can assess these theories in our growing understanding of the impact of life stress on our health. Examined in this volume are theoretical components that range from the impact of psycho-neuro-immunology on stress to the impact of psycho-social stress on gene expression, the role of neurobiology and its effects on traumatization and resulting psychopathology, to clinical models that aid us in understanding the process of experiencing stressful life events and the subsequent accommodation of stress in our lives. Examined as well is the role of stress and physical illness and efforts of clinicians and researchers to develop an integrative model in understanding the spectrum of stress phenomena, related to physical and mental illness. Personality variables are seen as moderating the relationship between stress and psychological or physical illness. Concepts such as psychological hardiness may play a mediating or buffer role in the accommodation of stress. Finally, current measures in the assessment of stressful life events are examined with special attention to the identification of experiences involving traumatization, consideration of the presence of coexisting psychological features, and specificity with respect to diagnostic and statistical evaluation criteria.