This Clean Technology Fund (CTF) case study presents lessons from the Theppana Wind Power Project in Thailand. To achieve sustainable long-term economic growth, diversify its energy mix, and reduce dependence on imported fossil fuels, Thailand has been promoting alternative sources of energy. Under its alternative energy and power development plans, the government aims to have 3,002 megawatts (MW) of wind power capacity installed by 2036, up from 7.3 MW in 2011. The Theppana Project was the first wind power project implemented by the local power producer, the Asian Development Bank’s (ADB) first private investment in wind power in Southeast Asia, and one of the first three wind power projects financed by a local bank. Construction began in September 2012, and the wind farm began commercial operations in July 2013. This case study describes the implementation of the Theppana Project and the challenges it encountered. It considers key questions including the importance of public private partnerships, and the role and impact of development finance in de-risking private investment and forging success. It assembles lessons learned to inform decision makers.