Street demonstrations had steadily decreased in South Korea after the country's democratization in 1987 and subsequent reform, but the country witnessed resurgence of a series of mass candlelight vigils since 2000. This study examines three competing theses to explain the individual-level sources of Korea's recent civic activism: 'disaffected radicalism,' 'social capital,' and 'Postmaterialism.' We used 2005 and 2010 World Values Surveys as well as the Lee et al. 2017 protest study to trace changes in protesters' characteristics and the motivations for protest over time during this period. Our results provide strong support for the Postmaterialism thesis and illuminate the evolutionary process of South Korean activism, demonstrating that the number of Postmaterialists has been slowly growing. The study confirms Inglehart's prediction that a nascent democracy will follow advanced democracies in an upward trajectory of elite-challenging activity and normalization of non-conventional participation by mobilizing traditionally inactive voters.