Commissioned 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 reverse the negative trends in the country's demographic development. To achieve this goal, a comprehensive study of trends in demographic reproduction and the interaction between individual processes was carried out by six working groups in the following main thematic areas: I. "Fertility 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 during 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 six volumes (one from each working group). The materials summarized in this multi-volume edition are extremely relevant and of paramount importance for the formation of an effective, stable, and sustainable demographic policy for the Republic of Bulgaria.