This paper considers opportunities for improved and expanded international development and transfer of climate technologies. It characterizes the economic scale of the climate technology challenge, and it reviews the pattern of public and private R&D and the rationale for R&D policies within the global innovation system. The paper clarifies the importance of options for inducing technology market demand through domestic GHG pricing, international trade, and international development assistance. It then turns to upstream innovation strategies, including international coordination and funding of climate technology R&D, and knowledge transfer through intellectual property. The paper concludes that a successful international effort to accelerate and then sustain the rate of development and transfer of GHG mitigation technologies must harness a diverse set of markets and institutions beyond those explicitly related to climate, to include those for energy, trade, development, and intellectual property.