The main purpose of this study is to analyze the Turkish Teachers' Union (TÖS), which started its activities within the framework of the rights defined after the adoption of the 1961 Constitution and was the first in its field, and its discourse, actions and effects between 1965 and 1975. The Teachers' Union of Turkey, which started life as an association under the leadership of Fakir Baykurt and took steps towards unionization, not only had the title of having the highest number of members among civil servant unions in its period, but also continued its activities during politically turbulent periods. This adventure, which started with the new constitution adopted in 1961, which had a relatively more libertarian understanding compared to other constitutions, was closed after the Memorandum of March 12, 1971. However, as a result of being the first in its field, the ideas and principles adopted by this union set an example for different union movements to be established after it. Within the scope of this study on this union, which played a leading role especially in education unionism, a general framework on the emergence of trade union movements in Turkey was established. Then, information was given about Fakir Baykurt, the founding president of the union, the Teachers' Union of Turkey and the way the union was organized. Subsequently, the union's activities, boycotts, demands and achievements between 1965 and 1971 were evaluated. Finally, the process of the union's closure within the scope of the March 12, 1971 Memorandum and the subsequent TÖS trials is discussed and the study is concluded with a general evaluation. This article analyzes the years of activity of the Turkish Teachers' Union in the light of relevant sources. Within the scope of the study, official publications, periodicals, publications of the union, academic studies and secondary sources were used in the writing of the study.