Dependency Theory posits that underdeveloped nations enrich advanced nations through an unequal global economic structure where core nations exploit peripheral countries. It originated in response to the failure of modernization theory to explain persistent underdevelopment. Key aspects include a core-periphery relationship where the core dominates through unequal exchange of resources, perpetuating the periphery's external dependency and underdevelopment. While subject to critique, Dependency Theory's emphasis on historical exploitation and structural transformation continues to inform debates on achieving more equitable development.