Mobile phone technologies have been hailed as a promising means for delivering mental health interventions to youth and adolescents, the age group with high cell phone penetration and with the onset of 75% of all lifetime mental disorders. Despite the growing evidence in physical health and adult mental health, however, little information is available about how mobile phones are implemented to deliver mental health services to the younger population. The purpose of this scoping study was to map the current state of knowledge regarding mobile mental health (mMental Health) for young people (age 13-24 years), identify gaps, and consider implications for future research. Seventeen articles that met the inclusion criteria provided evidence for mobile phones as a way to engage youth in therapeutic activities. The flexibility, interactivity, and spontaneous nature of mobile communications were also considered advantageous in encouraging persistent and continual access to care outside clinical settings. Four gaps in current knowledge were identified: the scarcity of studies conducted in low and middle income countries, the absence of information about the real-life feasibility of mobile tools, the need to address the issue of technical and health literacy of both young users and health professionals, and the need for critical discussion regarding diverse ethical issues associated with mobile phone use. We suggest that mMental Health researchers and clinicians should carefully consider the ethical issues related to patient-practitioner relationship, best practices, and the logic of self-surveillance.