The current interest in sustainability within international development presents an important opportunity for social work to further promote the often-overlooked social pillar of sustainable development. The dominant paradigm regarding economic systems of development and organisation has influenced not only the scope of sustainable development, but also an increasingly depoliticised vision of social work knowledge and practice. Inattention to structural determinants of social inequalities limits the scope for radical, sustained change. The Capability Approach’s recognition of poverty and development as complex, multidimensional phenomena aligns with social work values, while social work’s well-established and reflexive direct-level practice may provide the applied knowledge needed in the theory.