Childhood abuse (CA) has been found to be related to the development of a variety of psychiatric disorders in adulthood. Although CA is also associated with adult loneliness, few studies have investigated the role of loneliness as a mediator in the relationship between CA and adult psychopathology. Using data from a large, general population sample a mediation model was proposed and tested. Controlling for a range of background variables, the results from a series of regression analyses found that loneliness mediated the association between CA and six adult psychiatric disorders. The findings of this study highlight the importance of loneliness to the development of psychopathology. Theoretical and practical implications are discussed.