У дисертації висвітлено місце і pоль А. Яблоновського у становленні польської та української істоpичної науки нaпpикінці XІX – на почaтку XX ст., з'ясовано суспільно-політичні умови розвитку історичних знань на території польських та українських земель, котрі у другій половині ХІХ – на початку ХХ ст. входили до складу Російської та Австро-Угорської імперій. Виявлено фактори, що впливали на розвиток історичної думки зазначеного періоду. Проаналізовано організаційну та наукову діяльність польських історичних товариств упродовж зазначеного періоду, внесок їхніх представників у вивчення історії України. Проаналізовано твоpчий доpобок А. Яблоновського, зокрема монографії, статті, видання джерел, що відображають еволюцію історичної думки та погляди науковця на історію українських земель у контексті розвитку польської та української історичної науки. Висвітлено погляди А. Яблоновського на ключові проблеми української історії: походження та характер козацтва, назви «Україна»; рівня економічного розвитку українських земель у складі Речі Посполитої; становище українських замків, характер родинних стосунків в українських сім'ях у минулому тощо. Дослідження біографії науковця дозволило охарактеризувати його відносини з українськими істориками кінця ХІХ – початку ХХ ст. і з'ясувати місце А. Яблоновського в розвитку історичних знань зазначеного періоду, визначити внесок історика у розвиток польської та української історіографій.^UIn this thesis was highlighted the place and the role of A. Jablonowski in the formation of Polish and Ukrainian historical thought at the end of the XIX – beginning of the XX centuries, was found the socio-political conditions of the development of historical knowledge on the territory of Polish and Ukrainian lands at the specified time and was revealed the factors that influenced the formation of the historical thought of this period.The organizational and scientific activity of historical societies during the specified period, the contribution of their representatives to development of Ukrainian history were analyzed in the thesis. In this thesis were characterized such of scientific works as: monographs, articles, historical sources reflecting the development of historical thought and the scientist's views on the history of Ukrainian lands in the context of the development of Polish and Ukrainian historical science. In A. Jabłonowski`s varied historical writings certain basic ideas come to the fore. This is research the origin and organization of the Cossacks, the name «Ukraine»; the level of economic development of Ukrainian lands in the Commonwealth; the condition of Ukrainian castles and the specifics of family relationships in Ukrainian families in the past. The study of the biography of the scientist made it possible to characterize A. Jabłonowski's relations with Ukrainian historians of the late XIX – early XX centuries and to find out its place in the development of historical knowledge in this period about the past of Ukraine, determine the contribution of the historian to the development of Polish and Ukrainian historiography.Historical edition «Źródła dziejowe» became one of the largest editions in the Polish and Ukrainian historiographies of the nineteenth century. A. Jabłonowski and his colleague Adolf Pawinsky began issuing fundamental work on Polish and Ukrainian history – «Źródła dziejowe» at the end of the nineteenth century. This work was founded jointly by two historians as a serial publication. This work is an important collection of source material on the history of the Commonwealth. A lot of the materials published and worked out by historians concerned the history of Ukrainian lands that were part of the Commonwealth. In addition to the publication of historical source, this publication includes the monographs of A. Jabłonowski. In his works investigated the problems of the history of Ukrainian lands, such as the features of land relations in the 16th – 17th centuries, the processes of colonization, the existence of castles, the general issues of the development of Ukrainian lands – Volhynia, Kyiv region, Bratslavshchyna, Chernigivshchyna, Podillya and others. The historian and his work «Źródła dziejowe» has made an important contribution to the development of Polish as well as Ukrainian historical thought. «Źródła dziejowe» not only contained a subjective view of the historical development of certain Ukrainian lands, but also the original documents on the basis of which the historian came to certain conclusions in his studies.In the thesis we analyze the historical and geographical research of famous Polish historian A. Jabłonowski about territorial structure of Ukrainian provinces in the Rzeczpospolita in XVI – XVII century. His geographical research are showing in work «Atłas historyczny Rzeczypospolitey Polskiey», where the mapping form described the author's views on administrative features territorial structure of Polish and Ukrainian lands. In terms of modern historiography, the article identified deficiencies and value to the development of modern historical thought such works as A. Jabłonowski «Atlas historyczny Rzeczypospolitey Polskiey», «Zadnieprze» and others.The thesis highlights the views of the Polish historian Alexander Jabłonowski the peculiarities of Ukrainian culture, including its vision shows the influence of Polish culture in Ukrainian. According to the historian, important cultural achievements of the Ukrainian people – namely, the existence of the Kiev-Mohyla Academy, were associated with the influence of the Polish people, carrying the culture of the west Ukrainian lands. However, the historian points to the important historical significance Mohyla both the Ukrainian and the Polish people. This academy, according to A. Jabłonowski, enabled the further development of higher education in Ukrainian lands.The dissertation identifies a significant contribution of A. Jabłonowski in to the study of many important problems of the historical past of Ukraine. His creative legacy can be considered a significant step in the development of Ukrainian historical science in the second half of the nineteenth – early twentieth century.