Abstract"cross Western countries, more than a third of people will have a mental health disorder over their lifetime mood and anxiety disorders are the most common. The effectiveness of psychological interventions is well established. Cognitive "ehavioural Therapy C"T , for example, is as effective for mild and moderate anxiety as medications combined psychopharmacology and C"T is superior to either modality alone, suggesting a synergistic effect. However, C"T requires a major investment of time and resources. Thus, in public systems, C"T has limited availability and is subject to long waiting times primary-care physicians and psychiatrists may not offer C"T.Can technology address the deficiency of psychological interventions for mental illness? Internet therapies including smart phone apps have been developed, offering C"T and other psychological interventions. In this chapter, we focus on Internet-assisted C"T IC"T .IC"T allows patients to receive ongoing C"T with easier and quicker access, at reduced cost, and with increased convenience over traditional C"T. We review evidence from randomized trials and meta-analyses, which strongly support the use of IC"T in clinical practice, especially in combination with ongoing therapist support.We consider government experimentation with IC"T, with a particular focus on "ustralia. We also present a case demonstrating the clinical application of IC"T.Finally, with an eye to the future, we will look at potential research questions.