We examine the relationship between parental loss prior to age 17 years and adult psychopathology in 1018 pairs of female twins from a population-based registry. The relationship between loss and adult psychopathology varied as a function of the kind of loss (death vs separation), the parent involved, and the form of psychopathology. Increased risk for major depression and generalized anxiety disorder was associated with parental separation but not parental death and with separation from either mother or father. Panic disorder was associated with parental death and maternal, but not paternal, separation. Increased risk for phobia was associated with parental death and not parental separation. Risk for eating disorder was unrelated to the experience of parental loss. A model that includes parental loss as a form of "specified" family environment shows that, if it is truly an environmental risk factor for adult psychopathologic conditions, it can account for between 1.5% and 5.1% of the total variance in liability to these disorders and is responsible for between 7.0% and 20.5% of the tendency for these disorders to aggregate in siblings.