Recent efforts to forge a consensus on the role developing countries should play in reducing global greenhouse gas emissions have focused attention on climate friendly technologies (CFTs), most notably those that enhance energy efficiency. In the medium term, the effectiveness of technology-based climate strategies will depend critically on the rates at which CFTs diffuse in developing countries. This paper reviews some of the key findings of the economics research on technology diffusion and assesses the implications for climate policy. The most obvious lessons from this research are that widespread diffusion of CFTs may take decades, and that diffusion rates in developing and industrialized countries are likely to be quite different. In addition, the literature has implications for a number of strategies for promoting technology diffusion including information dissemination, factor price rationalization, and investment in human capital.