In the modern world order, which includes Eurasian and Iberoamerican areas, the formation and functioning of integration associations is subject to a common logic, which has been not identified comprehensively by science. The historical, geographical, political, and economic features of establishing specific associations should be taken into account in the process of studying the patterns of integration according to its role in configuration of the future association and regarding to objectives to be achieved. It is quite important to identify whether political or economic interests prevail as basic integration circumstances. The creation of integration legal order involves approximation (unification and harmonization) of laws in different fields. The creation of indivisible legal order is a big difference between integration associations and ordinary international organisations. There are many similarities between Eurasian Economic Union (the EEU) and MERCOSUR regarding to establishing processes. We are quite sure the movement towards so-called “integration of integration” will be enhanced in the nearest future.