The article deals with an increasing social and economic inequality in several regions of the world and inside particular states. In the present research, major attention is focused on social differentiation and uneven regional development that have been increasing throughout the past decades in Lithuania. Polarisation of the economic and social potential, tendency of residents to move to cities increase economic and social inequality between cities and peripheral territories. The increased EU investment flows for under-developing regions of Lithuania over the period of 2021-2027 providing conditions for reduction of economic and social differences of regions have been analysed.