Mental health problems are highly prevalent among adolescents, but a majority of adolescents is reluctant to seek help at mental health services because of shame and lack of anonymity. Intervening via chat (i.e. offering online support) could be a solution to remove these barriers and to reach adolescents. The dimensions of the RE-AIM model (reach, efficacy, adoption, implementation and maintenance) served as a guiding principle for discussing the potential of offering online support via chat. It appeared that the use of chat may be an appropriate way to reach adolescents and may have a positive impact on outcome measures related to mental health. Additional efforts are needed to stimulate adoption at the individual level (target group, intermediaries) and the organizational level. Future research needs to focus on the dissemination of chat-based interventions, differences between online peer support and online professional support, and the content of conversations via chat about mental health problems.