The aim of this doctoral thesis is scientific analysis, which will deal with Ustasha terror and genocide in the Independent State of Croatia on the example of Glina and Glina district during 1941-1942 by criticizing unpublished and published sources and interpretively consistent application of analytical methods. years. Although the doctoral dissertation covers the period from the establishment of the Independent State of Croatia to the first major crisis of the NDH government, its focus is on the period from May 1941 to June 1942, which deals with key historical events, which give the main character to the text structure. It is a period in which the Ustasha terror came to its main expression and grew into genocide. This is the time when the Ustashas, with the help and support of Nazi Germany and fascist Italy, who brought them to power in the proclaimed NDH, intend and try to completely eliminate Serbs, Jews and Roma in Glina and the Glina district. The United Nations Genocide Convention defines genocide as an intent or action taken with the intent to destroy a national, ethnic, racial or religious group as such, "in whole or in part". Intention, the fate of the target groups and physical destruction, as the three fundamental elements of the Convention, gain their full meaning only within the framework of one dynamic conception of genocide previously conceived as a process. Therefore, for the needs of the work, a genocidal process was conceived in the first two years of the NDH's existence (Ustasha terrorist organization in power – escalation of genocide – culmination of genocide – continuation of genocidal campaigns – the first great crisis of the NDH government). It is reflected in the composition of this doctoral thesis, which focuses on individual massacres and mass deportations of the population to the death camps of the Independent State of Croatia. By analyzing the state policy and decision-making factors at the macro (central), meso (regional) and micro (local) level, a dynamic picture of the genocidal process in Glina and Glina district during 1941-1942 was obtained aimed at destroying the Serbian, Jewish and Roma people as undesirable ethnic, religious and racial groups, all with the aim of creating an ethnically homogeneous Croatian state, politically and ideologically integrated into the "New Order" under the domination of Nazi Germany. By choosing microhistory as a historiographical method for investigating Ustasha terror and genocide, the current knowledge on the issues of how individual massacres and mass deportations to NDH death camps are connected with the macrocontext and how microhistorical analyzes of these crimes can provide understanding of Ustasha genocide as a whole. The doctoral thesis is based on three main sources: archival documents from the Croatian State Archives in Zagreb and the State Archives in Sisak, which have not been in historiographical circulation so far; published domestic and foreign collections of documents and memoirs, diaries and memoirs written by the actors themselves and participants in the events; conversations and correspondence with several survivors of the massacres in Glina and the Glina district. The obtained results of the research of Ustasha terror in local contexts are confirmed by three essential features of genocide: 1. it is not the nature of the act that determines whether genocide was committed, but its purpose; 2. the crime of genocide is directed at the collective, not at individuals; 3. The focus of genocide is not on the suffering of people, but on the physical destruction of a national, ethnic, racial or religious group. The great harmonization of state policy and decision-making factors at the macro, meso and micro levels has resulted in individual massacres and mass deportations to death camps being organized and systematic to a much greater extent than previously thought. The attacks on Serbs, Jews and Roma were institutionally and legally organized and implemented and directly related to the ultimate goals of the NDH. Given that the paper is based on the formulation and meaning of the Genocide Convention ("group destruction ... in whole or in part") and focuses on the physical destruction of undesirable social groups, using a microhistorical approach to researching the genocidal process, this doctoral thesis is methodological and content novelty in relation to previous research on Ustasha terror and genocide in Croatian historiography.