This study explored the patterns of activities and interactions among participants in the adoption process of a new system innovation, ADSL, in Korea, using an integrative framework of innovation system and strategic decision-making process for uncertainty reduction. An in-depth case analysis was undertaken to identify the adoption process of ADSL innovation, as a case in point, in conjunction with activities and interactions among related parties such as government, service providers, equipment suppliers, and content providers. The results of case analysis revealed that as the level of uncertainty in the adoption of ADSL innovation decreases, the focus of decision-making activities moves from scoping, to searching, to evaluating and to committing. Also this study found that at the early stage of ADSL adoption with higher level of uncertainty, government plays a pivotal role in coordination of related parties to participate in the innovation process, while service providers replaced this role at later stage of innovation with lower level of uncertainty. This study discussed theoretical and policy implications for the adoption of new system innovations with varying degrees of uncertainty.