The article analyses the concept of social and demographic development. These concepts are predominantly interpreted as a progressive movement towards a better state, as changes for the better in the quality of life and demographic characteristics of the population. According to the authors, positive demographic dynamics should not be evaluated only as progress, and negative - as regression, without taking into account the socio-economic context and the stage of demographic transition in a particular society. In the context of global demographic changes, including the large-scale spread of depopulation, a new idea of the demographic optimum is constructed, allowing for the absence of population growth and the priority of qualitative socio-demographic parameters (health status, level of education of the population, etc.). The study shows that demographic processes in different groups of countries pose serious social challenges. These challenges are specific to these territories and have a significant impact on their social development. At the same time, due to the commonality of key population shifts in more and less developed regions of the world, similar social consequences are likely to occur both there and there. The direct effect of life expectancy on the Social Progress Index (SPI) is found to be stronger in the global North than in the South. SPI is used as a composite indicator of quality of life, and the study found an inverse relationship between SPI and the rate of natural population growth. In the North, demographic rather than economic indicators are found to have a more significant impact on SPI.