Depression is associated with a formidable disease burden and has substantial economic ramifications. Its burden can only be partially alleviated through treatment. To make a more substantial impact on population health, we need primary prevention to reduce the number of new cases, and we need to do a better job about preventing relapses and recurrences. In this symposium we will present the latest evidence that prevention is a viable option: it is effective and cost-effective when offered as CBT-based self-help (bibliotherapy), and as preventive cognitive therapy for relapses and recurrences. The last couple of years witnessed a new approach to improving population health when some of these preventive interventions became available as internet-based interventions. These on-line interventions can be well structured and conducted either as pure self-help or with support by a therapist. We assume that on-line interventions are acceptable, because people can access these interventions in the privacy of their homes, at times they find convenient, and at a pace that suits them best. We also expect that these interventions can be cost-effective, especially when offered as self-help. Finally, we expect that on-line interventions have great potential to reach many people. It is therefore interesting to outline some of these new strategies and present evidence of their (cost) effectiveness.