The primary purpose of this study is to test whether dialogic interactions via SNSs can help revive political participation and help citizens to become involved in real-world politics. In a Tocquevillian sense, this study assumes a positive relationship between virtual associational life and political participation and therefore argues that SNSs today have become a new space for associational life, complementing the lack of face-to-face social interaction. Therefore, this study focuses on dialogic interactions on SNSs and examines the mobilization effect of SNSs with the assumption that dialogic interactions via SNSs revive on- and offline political engagement. Hence, this study explores the relationship between SNS use and political mobilization with the case of South Korea. Taking into consideration that South Korea's avant-garde position regarding the highest adoption rates of SNSs and a number of good anecdotes of SNS-mediated political activism, but the critically high political apathy among young generation, this study suggests that South Korea is the precisely matching example that embraces all issues raised by advocates and critics of cyber-democracy. This dissertation conducted two empirical studies to test the relationship between dialogic interaction via SNSs and political mobilization in meso- and micro-level perspectives. Chapter 6 analyzed the interactions between citizens and politicians in Twitter and found that dialogic interaction between citizens and politicians is positively associated to the mobilization capacity of politicians in the virtual space. Content interactivity is more effective in strengthening indegree influence in Twitter whereas interpersonal interactivity is more significant in attracting citizens' feedback. The findings imply that more responsive politicians can induce more citizens to engage in political activities in the virtual world. Chapter 7 aimed to extend the research findings of chapter 6 by examining the relationship between dialogic interaction and political mobilization at a micro-level analysis. The results presented that SNSs became a new outlet for political participation, in particular for extra-institutional forms of political participation. People who have greater number of friendships in SNSs, spend more time in SNSs, and perceive the virtual friendship more dialogic and interactive are more likely to be active in extra-institutional political participation. Furthermore, people who ever engaged in any political activity via SNSs are more likely to participate in offline political participation. The spillover effects are found from the virtual world to the real world and from extra-institutional forms of participation to institutional forms of participation. Thus, the results imply that SNSs may function not only as a new venue for new forms of political activities and but also as an incubator for the youth to engage in the political process of institutional political activities. The results may contribute to the larger debate on the political potential of SNSs and also open the door for further research. This study's finding can offer counter evidence to the criticism that the effect of SNSs and the Internet as a political mobilizer may be confined within only the virtual space. Furthermore, the results clearly present that the emergence of SNSs is reshaping the current power structure of political system by facilitating dialogues between citizens and politicians. Therefore, SNSs can make a significant contribution to positive relationship building between citizens and politicians and the benefits can be shared by both citizens and politicians. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]