The article examines demographic policy in the Republic of Kazakhstan as a process that is moving beyond narrow sectoral regulation and gradually becoming a space of multi-level governance linked to the strategic architecture of national development. The aim of the study is to assess the content of demographic changes during the independence period, their institutional logic, and their potential contribution to long-term demographic sustainability. The methodological framework combines a mixed research design with national statistics, international comparative data, strategic policy documents, and structural-comparative analysis. Demographic change in Kazakhstan is interpreted not as a mechanical sum of fertility, migration, urbanization, and ageing trends, but as an interconnected system in which each process amplifies or constrains the others. We argue that the current stage should be understood as a transition from growth to sustainability: population increase and relatively high fertility create a favorable window of opportunity, yet this advantage cannot become a durable demographic dividend without stronger social infrastructure, lower regional disparities, higher-quality migration governance, and institutional adaptation to population ageing. The article shows that the new substance of demographic policy must be tied to the reproduction of human capital, the mitigation of spatial imbalances, the strengthening of the care economy, and the development of data-driven regional governance. The findings demonstrate that Kazakhstan’s demographic sustainability depends not on the mechanical preservation of population size, but on the qualitative balance of demographic structure and the adaptive capacity of social institutions.