There is significant variance in the strategies of labor market flexibility under the same pressure of globalization. This article attempts to explain that variance by examining closely the Korean case, with particular attention to the response of labor, one of the most intractable actors in the reform process. After theorizing the nature of social welfare as a quasi-collective good and hypothesizing labor's responses based on Olson's theory of collective action, the study seeks to explain Korea's low commitment to flexicurity and the resultant dualism in the labor market. The core argument here is that the collective action problem among atomized corporate unions has led to high employment protection for regular workers in big business at the expense of marginal workers without appropriate social protection.