Дисертація присвячена комплексному дослідженню громадсько-політичної та наукової діяльності Марка Дмитровича Антоновича, йогоролі в житті української діаспори.Робота передбачає детальне висвітлення життєвого шляху молодшого представника відомої української родини Антоновичів – Марка Дмитровича. Визначено основні чинники, які сприяли становленню М. Антоновича як громадсько-політичного діяча та науковця. Окреслено його активну діяльність в УВАН у США та УІТ. Проаналізовано основні напрями його наукових досліджень та визначено його внесок у розвиток української історичної науки.^UThe thesis is devoted to a complex research of social, political and scientific activity of Marko Dmytrovych Antonovych, his role in the life of the Ukrainian diaspora.The study provides theoretical generalization of the issue and solves the actual scientific task that consists in determining the role of M. Antonovych, the outstanding Ukrainian historian, Egyptologist, publicist and socio-political figure. A noteworthy finding is that a small number of research was conducted during his lifetime. It was found that there is no monographic study of the life and work of the scientist, although the available references and sources create the basis for the reconstruction of his life and career. The source reference base is represented by scientific works, publicist and journalistic researches and reviews of M. Antonovych, published in various scientific journals, in particular, in the journal Ukrainian Historian (he was its co-editor), the newsreel Visti UVAN (News of UVAN), as well as in a vast number of other journals and studies (monographs). A separate part of the published sources is devoted to the publicist heritage of M. Antonovych. Memoirs of thescientist and about him (mostly published ones), as well as numerous letters (both published and those that will be introduced into scientific world), personal documents, autobiography, interviews, visual sources are of great importance.In the thesis the references to the biography of M. Antonovych are analyzed, the periodization of his life and activity is done on the basis of cardinal changes in the life of the historian, and many slightly known facts from his life are found. We believe that his development as the scientist, as well as public and political figure took place in the first two periods. The main factors that significantly contributed to the development of M. Antonovych as an outstanding individual were his family, general home atmosphere and socio-cultural environment ingeneral.On the basis of the supplemented bibliography of the works of M. Antonovych (including his journalistic works) it can be stated that the scientific and publicist heritage of the historian accounts 210 positions. Consequently, the range of scientific interests of M. Antonovych is also outlined. It is determined that the primary direction of his scientific activity was Egyptology, research of social and student movements, history of Ukraine, historiography, as well as literary studies, studies of the heritage of M. Hrushevskyi, etc.Thus, it should be highlighted that M. Antonovych is rightly called the first professional Ukrainian Egyptologist in the Diaspora. He managed to translate professionally a number of literary monuments of ancient Egypt with the creation of the terminological basis.