In this article, the authors discuss the experience of the EU in pursuing contract law harmonization in relation to similar developments in the Commonwealth of Independent States (hereinafter, "the CIS") and consider its potential learning effects for the processes in the CIS. They start by noting several key general features of the EU and the CIS (also making reference to some of the more advanced regional sub-groupings within the CIS) which bear on the comparability of the two formations; namely, the degree of diversity of member states, the level of economic integration achieved, and the strength of (common) institutions, insofar as they affect the issue of contract law harmonization in the respective regional formation.The authors continue by discussing the specific experience of the EU, followed by that of the CIS. In doing so, they distinguish between two main mechanisms: conflicts of laws unification and substantive unification. The main focus is on the instruments developed regionally (i.e., agreements and legislative acts as well as "soft" model laws), yet, the authors also note the membership in key instruments of international unification. Drs Dragneva and Ioriatti conclude by identifying a number of possible learning points for the CIS in relation to the substance or scope of the harmonization process, the instruments used for it, and the process of pursuing harmonization itself.