Initiation of the SMS dialogue also differed between clinical care and preventive health behavior interventions. All the preventive health behavior interventions in this review used researcher-initiated SMS dialogue, whereas the majority of the clinical care interventions used participant-initiated techniques. Participants in preventive health behavior interventions may not be motivated to initiate dialogue because they are healthy, unlike participants in need of clinical care intervention who are accustomed to regularly reporting to health professionals about their health status. Initiation methods may play an important role in participants’ perceptions of personal invasion and behavioral control, which may affect behavioral outcomes. Therefore, the SMS initiation method may be an important intervention element to explore further in terms of relative behavior change outcomes.