This study considers theoretical concepts pertaining to population migration broadly and the extent of its importance in our understanding of the mechanisms, types, directions and effects of migration. It analyses theories of migration on the micro and macro level and shows their development over time and the economic and social circumstances in which they emerged, in particular the emergence and development of the capitalist system and its strong relationship with waves of migration. It also assesses the relationship of this with the development of the phenomenon of urbanization. In the course of this analysis, the study makes comparisons between concepts and theories and shows their strong and weak points. So far as is possible, it considers their applicability to developing countries, including Arab countries. Its discussion highlights points of similarity and difference between these concepts and theories, and comes to some conclusions.