This article provides a comparative analysis of the legal regulation of labor migration in regional integration organizations: the European Communities (ECs) and the Eurasian Economic Union (EAEU). Methodologically, we argue that a synchronous comparison of the European Union (EU) in its current shape and the EAEU is rather inadequate and draw on a diachronic comparison of labor migration regulation in the EAEU and the ECs. On the one hand, we identify a number of important differences. We show, in particular, that while regulatory mechanisms in the EEC aimed at stimulating new migration flows, in the post-Soviet space mechanisms of regional migration governance provide the existing migration flows with an appropriate normative framework. We also show that in the case of the EAEU, the founding Treaty provided for a number of essential social rights for workers from EAEU Member States, whereas in the EEC these rights appeared at a much later stage. Regulation of labor migration in the EEC and the EAEU also differs in terms of distribution of competencies in this area between national and Community / Union levels. On the other hand, we also find a number of similarities, which hint at dynamics of policy learning. This is, in particular, evident in the development of mechanisms aimed at protection of migrants’ rights. This is also the case of the Agreement on pensions for workers of the EAEU member states, which seems to borrow from the EU experience opting for coordination of Member States’ retirement systems instead of their unification. Overall, some of EEC/EU ‘best practices’ have contributed to important positive developments in the regulation of intra-Union labor migration in the EAEU.