The primary focus of his work has been on urbanization and planning in cities of developing countries, with particular emphasis on Asian cities. Since the time of his doctoral research on land development in Jakarta, Indonesia (PhD Berkeley, 1992), Dr. Leaf has been extensively involved in urbanization research and capacity building projects in Indonesia, Vietnam, China, Thailand and Sri Lanka. The courses he teaches at SCARP cover the theory and practices of development planning and the social, institutional and environmental aspects of urbanization in developing countries.