Objective: To systematically review the literature with respect to treatment-seeking rates for depression and associated mediating factors. This review focuses on adolescents and adults of all ages. Methods: A structured literature review using Medline and PsychInfo databases revealed 38 relevant papers. Two trained reviewers independently and blindly assessed each study according to 4 inclusion criteria. A total of 17 papers met all 4 criteria. Results: Between 17.0% and 77.8% of individuals with depressive episodes or disorders sought treatment in these studies. We could explain the range in rates by diverse measures of depression, mediating factors that influence treatment-seeking, varied years in which the studies were done, and different time periods over which treatment-seeking was assessed. Conclusions: Treatment-seeking rates for major depression appear to have increased over the years. Age, race, social supports, and clinical and psychiatric factors seem to influence treatment-seeking rates most. Public health initiatives can use this information to facilitate service access and delivery.