This paper looks into the set of factors that develop the urbanization of the Philippines, a fastgrowing developing economy in South East Asia. The paper demonstrates that the “migration primacy urbanization model” is an appropriate one that is able to explain the urbanization case in the Philippines. The model draws supporting evidence from rank – size distribution analysis of major cities in the Philippines, a detailed examination of historical, geopolitical and economic forces which have evolved in the development of the Philippines as a sovereign state, and the applicability of the Todaro model on rural – urban migration to the Philippines. To address the problem of regional growth disparity, in particular the persistent growth divergence between the primate city of Metro Manila relative to other cities, a helpful policy prescription would be the adoption of a regional decentralization policy by the central planning authority. This should decentralize economic and population activities away from the primate city into other regional cities.