Abstract
This study examined the causal relationships among the issue agendas of three online news media in South Korea during two time periods. The issue agendas of the two online newspapers at Time 1 influenced the issue agendas of the online wire service at Time 2. The online wire service did not influence the issue agendas of the two newspapers during the same time periods. The leading online newspaper influenced the issue agendas of both the secondary online newspaper and the online wire service. The findings extend intermedia agenda-setting studies to the online environment.