Objectives The overall goal of the study is to deploy and rigorously evaluate the efficacy of Mobile Link, an innovative intervention to engage young FEWs in Cambodia through frequent SMS/VMs that link them to existing high-quality services including HIV testing. A 12-month randomized controlled trial (RCT) will be conducted to evaluate the Mobile Link intervention, with two arms of 300 FEWs each. FEWs will be equally randomized into one of two groups: (1) no intervention and (2) SMS or VM theory-based behavioral messages.