The objective of this article is to evaluate the Demographic Dynamics based on population expected and observed, in order to identify how vegetative growth and migration as determinants of population dynamics in Valle del Cauca behave during the census periods 1993 and 2005. The first results show that there is an overestimation of almost half a million people between observed and expected population for the Valle del Cauca. There is a differential between municipalities which shows a misunderstanding of the magnitude of rural and urban department, thereby generating changes in the urbanization process.