eMental health refers to the use of eHealth in mental healthcare. In this chapter, a definition, aim and brief history of eMental health are provided, but the main focus lies on practical application and evidence for this area of application. The chapter discusses possibilities and challenges of this field. The chapter contains explanations and examples of treatment within eMental health, such as web-based and mobile interventions, blended care and virtual reality. Also, evidence of the effectiveness of each method is provided, partly by means of giving concrete examples. The chapter ends with implications of these results, a look at the future of eMental Health, and its accompanying concerns, both practical and ethical.