He has focused in recent years on strengthening health systems in developing countries, and on specific issues in the economics of HIV/AIDS and other infectious diseases. At the World Bank, 1980-97, and Futures Group, 1997 to present, he led HIV/AIDS analyses on costs and financing for many of the seventy countries in which he has worked. He is author or editor of three books and several dozen articles. He has offered technical support to UNAIDS, UNFPA, and The Global Fund.