This study questions one of the main wheels of the Ottoman central authority, the kapıkulu institution, and its organizational features in terms of their human factors under the three main categories through three distinct case studies. For the first, it investigates the conscription methods of the devshirme system, by which the future military and administrative cadres of the Ottoman state were selected. Secondly, it examines the administrative and organizational structure of the kapıkulu institution. Thirdly, it scrutinizes the roles of the kapıkulus in the state’s fiscal organizations. This study has been shaped by the contents of archival documents from the Prime Ministry Ottoman Archive in Istanbul, the Saint Cyril and Methodius National Library of Sofia, and the Tapu Kadastro Genel Müdürlüğü Arşivi of Ankara. These are conscription registers from late fifteenth and early seventeenth centuries, a mevâcib (salary) register of the kapıkulu regiments from the first quarter of the sixteenth century, a muhalefât (probate) register of the Janissaries from the early seventeenth century, and the fiscal registers of nüzül, mukataa, iltizam, and tahrir from the sixteenth and seventeenth centuries. These sources have been evaluated in three case studies in line with the three main categories questioned and examined in this thesis.