There is widespread concern that unconventional methods of civic engagement, exemplified by demonstrations and strikes, harm the development of democratic institutions. During recent decades, however, unconventional methods of civic engagement has been on the rise in Korea as well as in western democracies. The increasing tendency of unconventional civic engagement has been fueled by the development of IT technologies including Internets and mobile phones, which help reduce the transaction costs of gaining information, expressing policy ideas, and organizing policy movement groups. This paper addresses the developmental trajectories of unconventional methods of civic engagement in Korea by deriving from the core insights of sociological institutionalism and Internet-based civic engagement, which are cognitive legitimacy and long tail politics. This paper argues that unconventional methods of civic engagement gain cognitive legitimacy from society and Internet-based long tail politics help make these methods comprehensible and taken-for-granted.