A random sample of 247 Canadian single mothers currently receiving social assistance participated in a study designed to: a) provide a comprehensive description of mother’s lifetime exposure to 11 adversities, four psychological traumas, and eight assaultive traumas; b) examine the association between exposure to childhood and adulthood adversities and traumas, and mother’s current post-traumatic stress symptom. Of those surveyed, 31% met the criteria for a probable PTSD diagnosis. Between 78% and 80% reported 1 or more lifetime adversity, psychological trauma, and assaultive trauma. Rates of adversities were similar to the general female population. However, rates of psychological and assaultive trauma were six to ten times greater than the general female population. Results show that level of exposure to psychological and assaultive traumas, but not adversity, differentially impacted both the patterning and severity of mothers’ current PTSD symptoms. Psychological trauma exposure was the only event type that differentiated the mean scores for the re-experiencing, avoidance/numbing, and hyper-arousal symptom clusters. While exposure to assaultive trauma differentiates mean scores primarily for the avoidance/numbing symptoms cluster. Implications for health promotion initiatives across health and social service sectors are discussed.