Assigned by the Council of Ministers of the Republic of Bulgaria, the project "Measures to overcome the demographic crisis in the Republic of Bulgaria" aimed to conduct a comprehensive review of population development in Bulgaria and to propose specific measures to change the negative trends in demographic development. To achieve this goal, a comprehensive study of trends in demographic reproduction and the interaction between the individual processes was applied, which was carried out by six working groups in the following main thematic areas: I. "Birth rate and family policies"; II. "Mortality, aging and quality of life"; III. Migration and National Identity; IV "Demographic development and labor resources"; V. "Vulnerable ethnic and religious groups and communities"; VI. "Demographic policy in Bulgaria in the period 1879 - 1989. As a result of the activities of each working group, specific measures were identified to overcome the existing problems in the respective demographic area. The final material was published in 6 volumes (one from each working group). The materials summarized in this multivolume edition are extremely relevant and of paramount importance for the formation of an effective, stable and sustainable demographic policy of the Republic of Bulgaria.