A variety of effective interventions exist for people who are willing to seek help for depression. However, there is a lack of interventions for individuals who are not willing to seek help or follow through with treatment recommendations. This is the first population-based intervention for depression that is appropriate for individuals in all stages of change—not merely the minority who are prepared to take action. Two primary care samples were included: 1) patients at risk for or experiencing depression but not involved in or planning treatment (Untreated Sample), and 2) patients newly prescribed antidepressant medication (Antidepressant Sample). Patients from both samples were randomly assigned to receive the intervention consisting of telephone assessments, a stage-based workbook, and three individualized, computer-generated reports mailed to the home (n=443), or usual care (n=459). Primary outcomes, assessed at 9 months, were change in depression severity, reliable and clinically significant change in depression severity, stage of change for using effective methods or prevent or reduce depression, onset of major depression if experiencing only subclinical symptoms at baseline, and medication adherence. The study design included an examination of whether the intervention effect was moderated by primary care sample, baseline use of effective methods to prevent or reduce depression, and level of depression.