Biomass resources account for about 11% of the global primary energy supply (Goldemberg,2000) - their contribution is even greater, and hence particularly important, in developing countries (Reddy, 2000). But biomass utilization in these countries generally takes place with alow end-use efficiency, often in rural households, informal small-scale or even small and medium enterprises in the organized sectors. Additionally, biomass can be used for providing modern energy services for basic needs and productive applications in areas that are lacking these, but this aspect of biomass use has not been tapped much yet. Gasifier technologies offer the possibility of converting biomass into producer gas, an energy carrier, which can then be burnt for delivering heat or electrical power in an efficient manner (Kartha and Larson, 2000). While this approach could make a contribution to helping solve the energy problem in developing countries, such potential can be meaningfully realized only with the large-scale deployment of biomass gasifierbased energy systems (GESs). This has not happened yet. This report explores the reasons for the lack of scale -up, using India - a country with a longstanding and extensive gasifier development and dissemination program - as a case study. Then, drawing on the Indian experience and lessons from it, it discusses in detail various issues that are of particular relevance to scaling up gasifiers-based energy systems. It also proposes specific applications and contexts in which it might be particularly fruitful to explore large-scale deployment of such energy systems, and ways in which this might be done.