This document discusses the use of mobile devices and mHealth in developing countries. It outlines how mobile phones, smartphones, and tablets can be used in environments with affordable cell phone access and expanding networks to perform traditional public health functions like data collection, behavior change communication, diagnostics, disease surveillance, and supply chain management. It also discusses how organizations like HKI use simple mobile tools for health monitoring, evaluation, and community health worker support to obtain better data, reach more people, and respond more rapidly. However, it notes that mHealth requires careful planning, significant training, and consideration of factors like electricity access and literacy.