This chapter provides some background information and suggestions for disability management professionals. Workplace mental illness has become an issue of growing concern to the disability community. The World Health Organization estimates that by the year 2020, depression will be the most common cause of disability in the world. One of the most serious consequences of occupational stress is mental illness, an aspect of occupational health that is receiving increasing attention. The Diagnostic and Statistical Manual of Mental Disorders (DSM) provides guidelines of clinical criteria related to diagnosable disorders. Often, a DSM diagnosis is the requisite criteria for disability benefits related to issues of mental health. A diagnosis of post-traumatic stress disorder (PTSD) requires that an individual experienced, witnessed or was confronted with actual or threatened death, serious injury or threat to physical integrity of oneself or others. A symptom that may distinguish PTSD in the process of differential diagnosis includes increased irritablility or hostility, hypervigilance and an exaggerated startle response.