Two major approaches have dominated the field of the sociology of development: theories of modernization, which focus on developed countries, and theories of development, which concentrate on Latin America, Africa, and East Asia. The social transformations in China, Russia, and the other European former socialist countries since 1989, however, have challenged both the traditional approaches of Sociology of Development with a series of new issues: how should one evaluate the various pathways to development in different countries and regions? how should one examine the state - society relationship in social development and transition? how can one deal with the social inequality in the process of development? These topics have expanded the scope of the Sociology of Development and provided an opportunity to construct new theories. The author suggests that, in response to the practice conditions of ongoing socio-economic transformation, new theories of transition, in addition to theories of modernization and theories of development, is the imperative need in the field of the sociology of development.