Rapid and uneven urban development has been one of the most important social problems and complications of developing countries after the Second World War. The explosive growth of the cities is the result of continuous migration of rural to urban areas which one of its socio-economic and physical consequences is expansion of slum dwelling. Regardless of living in the outskirts of the city, slum dwellers are not merged in the culture, economy and community of the city. They form a new social pole. This study is a survey on the affecting socio-economic factors on cultural differences between slum and urban youths (18-30 years old) in the city of Shiraz. Implemented theory is a synthetic understanding of the suppositions of Oscar Lewis, Park and Burgess, Rogers and Claude Gruen. Mate selection, familism, patriarchy, and religiousity are our criteria to study the cultural differences between slum and urban areas. It is a cross sectional survey. Its data collected by a questionnaire from 405 Shiraz city youths, selected by cluster sampling method. Multiple regression analysis denotes that mother's occupation, father's occupation, media, size of household, youth's education, and mother's education in the urban areas, father's occupation, media, youth's education, income, size of household for the slum dwellers, and media, father's occupation, size of household, and youth's education for the whole sample are the variables which describe the cultural changes. These variables describe 70 percent of urban dwellers', 61 percent of slum dweller's and 78 percent of the whole sample's variation of the dependent variable.