The present paper is part of a wider research on Romania’s integration in the economy of Europe in the 19th– 20th centuries. It is based on an ample Romanian and foreign literature, but also on a significant number of quite new documents that have become available as a result of the opening, in the summer of 2006, of the Central National Archives of Romania on Comecon issues. The purpose of the paper is to underline the aspects connected to the evolution of the idea and practices of integration. In the well known circumstances of the end of the Second World War Romania belonged to the Soviet sphere of influence and, for almost half a century, it has been part of the socialist system.