Mobile health (mHealth) interventions are rapidly gaining popularity for their potential to improve public health, and many developing countries see them as an important resource for frontline health workers (FHW). However, best practices for implementing and evaluating the effectiveness of programs and projects is lacking. This report summarizes current data from over 140 FHW-supported mHealth projects from developing countries to describe the emergent trends and best practices in the use of mobile phones, tablets, and technical platforms by FHWs over the last decade, understand the key considerations in choosing the type pf phone and platform and associated programmatic costs, present the evidence on the effectiveness of mobile approaches, and establish a framework for systematically deploying such tools.