OBJECTIVE: To review published reports on Web-based treatment and prevention programs for depression, anxiety, and suicide prevention in children, adolescents, and emerging adults. METHOD: A systematic search of the PsycINFO, PubMed, Medline, and Web of Science databases was conducted in December 2013. Programs were classified according to evidence-base level (Well-Established, Probably Efficacious, Possibly Efficacious, Experimental, and Of Questionable Efficacy). RESULTS: Of the 14,001 citations initially identified, 25 articles met inclusion criteria for Web-based interventions. These described 9 programs, of which 8 were Internet based and 1 was a mobile application. No Web-based interventions for suicide prevention were identified. Of the randomized controlled trials (n = 14) and open trials (n = 3) identified, 10 reported significant postintervention reductions in symptoms of depression and/or anxiety or improvements in diagnostic ratings, with small to large effect sizes. Many of these studies also reported significant improvements at follow-up. The methodological quality of the studies varied. Many programs were limited by their small sample sizes and use of waitlist or no-treatment control groups. CONCLUSION: There is limited evidence for the effectiveness of Web-based interventions for youth depression and anxiety. Additional research and program development are needed to fill the current gaps in the literature.