The Commonwealth of Independent States (CIS) was designed to manage the collapse of the Soviet Union and foster post-Soviet cooperation in political, economic, and security spheres. Over a decade into its existence, most analysts would rate it a failure: many post-Soviet states do not participate in CIS ventures, the institutional machinery of the CIS is weak, and Russia, the most dominant post-Soviet state, has tended to favour bi-lateral relationships over multi-lateral institutions. Why is this the case? This article looks at the CIS through the prism of theories of regionalism, demonstrating that the CIS was handicapped on many fronts, including emergent multi-polarity in the post-Soviet space and domestic-level political considerations in many post-Soviet states.