The Second World War brought radical changes in the shape of Poland, such as extermination of Jews and a large number of Sinti and Roma, and loss of eastern areas of Poland with their national minorities. Changes in social consciousness such as strengthening of national self-identification under the influence of war, and policy of the occupants and not acknowledging national minorities to be a part of the Polish nation were also of vital importance. In the communist Poland these mentality changes were not being researched. The first stage which had an influence on the national structure of post-war Poland was forced migration in the first years after the war. One of the reasons for it were territorial changes and compulsory displacement of German residents. This phenomenon is not connected with the national minorities subject. Another reason was a process of national homogenization of Central European countries, sometimes called ethnical purges, although it would be better to use the expression „etnonational”. Since the end of 1944 and the beginning of 1945 there was a two-way process of building the state of Poland, in which there would be no national minorities, and nationality and citizenship would be identical. Despite apparently large political changes in Poland, which were taking place since the turn of the forties and the fifties until the seventies, Polish nationality policy of all that period was constant. It was applied by various means depending on political and social conditions. In the eighties no new concept of the nationality policy was created. The policy changed according to current political needs or when it was raised by the opposition. The authorities continued the previously elaborated policy (administrative limitations, surveillance) to the extent to which the unstable situation allowed. A symbol of a breakdown of the previous policy and taking over the initiative by the opposition was the creation of the Committee for Co-operation with National Minorities (with Marek Edelman as a chairman) within Citizen Committee at the Chairman of NSZZ „Solidarność” (The Independent and Self-Governing Trade Union Solidarność).