Abstract. One of the most challenging developments for students of international relations is the resurgence of ethnic strife, including secessionism and irredentism. Basic questions are only beginning to be addressed in the post‐Cold War era. Why are some states more likely than others to intervene in ethnic conflicts? How can international norms about third‐party intervention in ethnic conflicts be evaded or ignored by some states but respected by others? Why are some states inclined to use force rather than mediation to resolve ethnic strife? In short, what accounts for the emergence of adventurous and belligerent foreign policies with respect to internal ethnic conflicts? These questions are of increasing importance to students of international politics, yet the dynamics and internationalisation of ethnic conflict are far from fully understood. This study focuses on the dynamics of third‐party intervention in ethnic strife and implications for peaceful resolution. The first section presents a model that identifies the general conditions under which ethnic strife is most likely to lead to intervention by third‐party states. The second uses four cases to illustrate, within the context of the model, different processes with respect to internationalisation of ethnic conflict. The third and final stage identifies implications for policy and theory, along with directions for future research.