Showing great similarities in terms of their geography, size, economic structure, development and demography, Estonia, Lithuania and Latvia, which are called the Baltic States, have positioned themselves on the side of the Western system, as a part of it, with the collapse of the Soviet Union, under whose rule they lived for many years. While restructuring their economic, cultural and political structure as members of the European Union, these states have determined their military and security structure as members of NATO. It was clear that while these three Baltic States were integrating into the Western system with all their structures, they would naturally face some difficulties. Therefore, adaptation studies have encountered different levels of difficulties and obstacles in each state. For this reason, there were different consequences of being involved in both structures. It is also seen that although each state is referred to by one name and has different dynamics, similar conclusions cannot be reached when integration is completed in these three countries. The purpose of this study is to examine the “positive and negative” developments in the economic, cultural, political and military fields of the EU and NATO memberships in the mentioned states.