In this paper, basic characteristics of demographic and economic changes in the area of Belgrade agglomeration in the second half of 20th century has been researched, and a global trend of their establishments and motions has been indicated. Changes of territorial arrangement, spatial distribution and structural features of population, within the agglomeration itself, were in close interaction with directions of development and expansion of urban region. Belgrade agglomeration development follows several stages in its physiognomic-spatial, economic and demographic growth, whereby the migrations, as in cases of all large urban systems, had special influence on growth and structural features of population. In this paper, modern development processes and their effects on demographic growth have been emphasized. .