When the International Criminal Court (“ICC” or “Court”) was established in 2002, states, nongovernmental organizations (“NGOs”), and the international community had extraordinarily high expectations that the Court would bring an end to impunity and provide broad-based accountability for international crimes. Nearly five years later, those expectations remain largely unfulfilled due to political constraints, resource limitations, and the limited ability of the ICC to apprehend suspects. This article offers a novel solution to the misalignment between the Court’s limited resources and legal mandate on the one hand and the lofty expectations for it on the other, arguing that the Court must engage more actively with national governments and must encourage states to undertake their own prosecutions of international crimes. It advocates a shift in the ICC’s role through a policy of “proactive complementarity,” whereby the Court would encourage and at times assist states in undertaking domestic prosecutions of international crimes. The article examines the legal mandate for such a policy, considers the political constraints on the Court, offers a practical framework for the implementation of proactive complementarity in the range of circumstances the ICC is likely to face, and documents examples of proactive complementarity in the ICC’s initial operations. Overall, the article argues that encouraging national prosecutions within the “Rome System of Justice” and shifting burdens back to national governments offer the best and perhaps the only ways for the ICC to meet its mandate and help end impunity.