India is undertaking a large-scale program to provide housing for low-income residents throughout the country. Many partsof the country are in tropical high-temperature climates, but air conditioning is not economically feasible in these parts. In cooperationwith a local research foundation in Western India, the authors have been participating in the analysis, design, and testingof several prototype housing units. The research has stressed the integration of thermal mass, insulation, roof design, and naturalventilation strategies to achieve thermal comfort without the use of mechanical cooling. Full-size test structures have beenconstructed and detailed measurements have been made of thermal conditions. The designs have included several concepts forthermal insulation using indigenous low-cost materials. A focus of the research has been on the development of innovative roofsystems. These include multilayer structures that allow for air circulation, radiation heat transfer control, and providing mechanicalstrength. Experimental results have shown that even in severe arid climates the interior conditions can be substantially moderatedthrough most of the operating hours. The results of this research will be an important contribution to the designs of the initialphase of large-scale housing construction over the next few years in Western India.