Planning the electric power system for postwar South Korea involved many powerful actors such as the United States Agency for International Development (USAID), American technology advisory groups, the Korea Electric Power Company (KEPCO, the nationalized electric utility company), relevant Korean-government agencies, and of course Korean geographical and material settings. While all the involved parties agreed on the need to devise a “rational” plan, they needed a long process for negotiating their different ideas about what was economically, politically, and technologically rational for South Korea. This paper examines strategies and different technological styles that produced an agreement on the new power development plan in South Korea, by focusing on various conflicts between different parties. In the end, they reached a loose consensus on the rational power development plan. It was not about balancing the supply and demand of power, but about negotiating each others’ different economic strategies in the world system and economy. Also, it was not only about calculating economical mixture of thermal/hydro power plants, but also about persuading each other over the proper technological styles.