INTRODUCTION: In 1921-1939, Volyn – a historical Ukraine region that, at the time, was part of Poland (the Second Polish Republic) – was at the epicenter of radical political, socio-economic and cultural transformations. As in other parts of the Polish state, architectural activities played an important role in their visualization. The change in the quality and structure of the environment at the material level reflected the architectural trends and social order of the time. In terms of quantity and, sometimes, quality, buildings constructed in the interwar period in Volyn differ signifi- cantly from the legacy of the interwar period in other regions of modern Ukraine. The explanation lies in the region’s weak “starting” socio-economic position for future development and the modest role of the largest cities in the region (Lutsk and Rivne) in the national economy of the Polish state. For obvious reasons, there was a significant shortage of specialists in the architectural sphere in the region, which hampered its development and reduced the artistic and aesthetic qualities of the designed objects. Since the beginning of the 21st century, the interest of researchers in the architectural heritage of the Avant- garde in Volyn has increased significantly. The research is carried out against the background and under the obvi- ous influence of a wide global interest in the architecture of the 20th century. There is a consistently high activity of Polish scholars in the sphere of interwar architectural heritage in European and global contexts. The analysis of the development of the architecture of the Second Polish Republic in the context of similar processes in Western Europe was carried out by P. Begansky, R. Tschetsyak and P. Krakowski. The problem of architectural innovation in ARCHITECTURE OF AVANT-GARDE IN UKRAINE IN 1921-1939: ORIGINS, WAYS OF SPREADING, MAIN FEATURES Case study of Volyn Olga Mykhaylyshyn ABSTRACT: The heritage of the architectural Avant-garde in Ukraine, formed in the interwar period (1921-1939), is large-scale in the number of objects and diverse in their typology, techniques and forms of expression of modern architectural ideas. Volyn – a historical Ukraine region that, at that time, was part of Poland (the Second Polish Republic) – plays a special role in this context. To date, the region has preserved a significant array of objects that demonstrate the specifics of the interpretation of European and Polish Avant-garde concepts. The article attempts to analyze the architectural context, ways of spreading and formation features of the architectural image of residential and public buildings as part of the European heritage of Interwar Modernism. Lack of professional evaluation and recognition of the objects’ value leads to their gradual degradation, reconstruction or destruction. Methods of comparative and stylistic analysis, archival research and field surveys of architectural objects were used in this research. The study showed that the spread of the Avant-Garde style in the architecture of Volyn was significantly delayed compared to similar processes in the architecture of Western Europe and Poland and reached its peak at the end of the interwar period. The use of formative techniques of Avant-Garde architecture in housing construction became an identifier and symbol of the social prestige of certain social groups. The design of public buildings reflected Volyn’s rapid social modernization. KEYWORDS: Architecture, Avant-garde, Heritage, Volyn, Ukraine 56 JOURNAL 67