Over the last several years, there has been a substantial increase in the number of publications reporting on Internet interventions for mental health and addictions. This paper provides a summary of the recent research on Internet interventions for the most common mental health and addictions concerns-depression, anxiety, alcohol and smoking. There is considerable evidence for the effectiveness of Internet-based interventions targeting depression, anxiety disorders, alcohol use and smoking. Small to moderate effect sizes have been reported for interventions targeting depression, anxiety and alcohol use, and smoking interventions have shown large effects. The addition of human support to depression and anxiety interventions has generally resulted in larger treatments effects, but this trend has not been observed in trials of interventions targeting alcohol use. There is some evidence that online interventions can be as effective as face-to-face therapies, at least for anxiety disorders. Despite a proliferation of research activity in this area, gaps in knowledge remain. Future research should focus on the development and evaluation of interventions for different platforms (e.g. smartphone applications), examining the long-term impacts of these interventions, determining active intervention components and identifying methods for enhancing tailoring and engagement. Careful consideration should be given to the ongoing technical and clinical expertise required to ensure that Internet interventions are delivered safely and professionally in a rapidly changing technology environment.