There is substantial enthusiasm for the concept of mobile health (mHealth), a broad term typically used to describe the use of mobile telecommunication technologies for the delivery of health care and in support of wellness. In 2011, US Secretary of Health and Human Services Kathleen Sebelius referred to mHealth as “the biggest technology breakthrough of our time” and maintained that its use would “address our greatest national challenge.”1 This level of exuberance for mHealth is driven by the convergence of 3 powerful forces. First is the unsustainability of current health care spending and the recognition of the need for disruptive solutions. Second is the rapid and ongoing growth in wireless connectivity—there now are more than 3.2 billion unique mobile users worldwide—and the remarkable capability this brings for the bidirectional instantaneous transfer of information. Third is the need for more precise and individualized medicine; a refinement in phenotypes that mandates novel, personal data streams well beyond the occasional vital sign or laboratory data available through intermittent clinic visits.