Lukasz LEWKOWICZ Departament of Political Science Maria Curie-Sklodowska University, POLAND No 10 FORMS OF TRANSBORDER COOPERATION IN THE REGION OF THE TATRA AND SUB-TATRA MOUNTAINS. THE PAST AND THE PRESENT 1. INTRODUCTION The Tatra and Sub-Tatra Mountains are culturally one of the richest regions in Poland and Slovakia. It is the mountain area, which has never divided, but rather integrated the multicultural communities living there. Cultural and language vicinity and common historical heritage influenced the development of relations between the borderland inhabitants. It caused, as early as in 1920s, the beginning of the first transborder territorial units. They usually involved the protected areas and the tourist conventions. At the beginning of the 1990s, the process of extending the institutionalization of the transborder cooperation began in the region. As a result, in 2007 the Tatras Euroregion evolved into the European Grouping of Territorial Cooperation. The aim of this article is to analyse the most important ways of transborder cooperation in the region of the Tatra and Sub-Tatra Mountains after 1918. The analysis will be conducted chronologically and divided into stages. The subject of the first part of the research will be the Polish- Slovakian transborder cooperation during the interwar period. The next analysed period, in which few transborder initiatives developed, will be the communist period. The last part of the article will be devoted to the profile of the Tatras Euroregion, as well as the new, legal European Union institution – the European Grouping of Territorial Cooperation, in which the aforementioned Euroregion is going to transform in the nearest years.