The economy and demography of the Arab states in the Gulf Cooperation Council (GCC) are bound together by petroleum. Each is still registering great demographic growth, both in comparison with global averages and amid developing nations with high rates of population growth. This paper sheds light on the current reality and evolution of population sizes in the GCC states through the first decade of the 21st century. The paper then examines factors underlying the changes. It then goes on to discuss the demographic consequences of these developments during a period when demographic changes were expected to have settled, following decades of construction that made migrant workers an urgent necessity. The study seeks to understand developments in the manpower sector in general, with a focus on the growth of the contribution of indigenous (citizen) manpower. The paper examines and analyzes general data collected locally from the six GCC states, along with international and regional resources, and the findings of a variety of recently published studies on the subject.