This paper re-examines the facts and theories of the much debated population transition and proposes that the transition should be regarded as a “regularity” governing the population growth of the nations during the past two hundred years. It is argued that since in almost all the cases the mortality decline has preceded the fertility decline but Socioeconomic covariates of fertility have been found to be inconsistent, a supply dominant resolution with built-in dynamics of the renewal process should be adopted. Fertility decline is then related to a subjective increase in the supply of children, and alternatively, to the relative income of the young adults entering the labor market. Evidences affirming the relationships between mortality decline, shifting age composition, and ferti1ity decline are provided.