In the past 10 years, the global campaign to expand treatment for millions of people with AIDS living in resource-limited countries, especially in sub-Saharan Africa, has gained substantial commitments in public and private financing, and has made major strides in making treatment available to those who need it. A new collaborative study by researchers at Weill Cornell Medical College and the Clinton Foundation HIV/AIDS Initiative explores how to combine engineering science with medical care to guarantee the long-term success of these treatment programs.