Developing countries face steady growth in the prevalence of chronic diseases, along with a continued burden from communicable diseases. “Mobile” health, or m-health—the use of mobile technologies such as cellular phones to support public health and clinical care—offers promise in responding to both types of disease burdens. Mobile technologies are widely available and can play an important role in health care at the regional, community, and individual levels. We examine various m-health applications and define the risks and benefits of each. We find positive examples but little solid evaluation of clinical or economic performance, which highlights the need for such evaluation.