There is an urgent need to develop and implement more effective responses to HIV/AIDS for migrants and mobile populations. Such responses should empower these populations to protect themselves against infection, provide them with care and support, and reduce the onward transmission of HIV. This document briefly describes both the challenges involved (increased vulnerability and risk-taking, and lack of attention and resources) and some possible effective responses. It also gives examples of successful interventions that address the issue of migration and AIDS, such as the Mothusimpilo Project in Carleton, South Africa.