The teacher`s effect on improving schools and education in Serbia, and later in Yugoslavia, has always been remarkable. Gathered around their estates association, since the eighties of the 19th century, they have worked on improving the quality of teaching, financial status of teachers, education and training of teaching staff and to provide local and international contacts. The Regulations of the Association was adopted at the founding congress of the Yugoslav teachers` association on 17 and 18 July 1920th in Belgrade. Among other things, the goals of Association were the activities which based of political and religious liberty, and the development of cultural relations with other similar associations. It was seen that, from the beginning of JUU (YTO Yugoslav teachers' association), international cooperation played an important role. As a member of the International Association of Teachers' they had intensive partnerships with France and Czechoslovakia. In 1922 French society was initiated the cooperation, next year the members of the Association attended the First International Congress in Paris, and the 1927th Association took part in the World Congress of primary education in Paris. In 1923 Yugoslav and Czechoslovak teachers organized a meeting and exhibition entitled "Cultural mission schools in the nation and the state" in Bratislava, and the 1927th Czechoslovak teachers from Brno visited Belgrade. Belgrade has hosted, in 1936, the International Teacher Conferences, and was the place where the Declaration about the coming German Nazism was adopted. The aims of this paper are to draw attention on two important moments in international cooperation YTO. In the first place it was the exchange of professional ideas that seemed to improve the quality of teaching and the development of pedagogical science, and raising the cultural level of the Serbian teachers. Another important characteristic is their relationship to the political developments in the country and in Europe, their participation in wider social trends.