According to existing theories of digitally networked collective action, well-connected actors play a central role in protest mobilization. A number of recent studies have challenged this view by showing that peripheral actors may play a more important role in the spread of digitally networked protest. However, case selection has made it difficult to evaluate the scope conditions of peripheral mobilization. This study contributes to the literature by examining the association between peripheral coordination and protest in Japan and South Korea. Drawing on a novel data set containing protest counts and individual-level social media communication across notable periods of protest in Japan and South Korea, this study shows that peripheral communication is positively associated with protest activity in both countries. Contrary to previous research, these results suggest that protest is a complex contagion even in industrialized East Asian democracies.