The question of how to sustain human development in the current ecological and institutional landscape is arguably one of the utmost scientific and administratively challenging contemporary dilemmas. In response to this issue, the concept of Sustainable Development was proposed by the United Nations to inform policies for societal and human development. However, for national governments, the prevalent sustainability schemes summon more confusion than coherence. This is due to the frequent and inconsistent ways the concept of sustainability is put into practice, and consequently, difficulties in measuring and managing sustainability. The ability to evaluate how sustainable public projects are, will remain deficient if sustainability remains a notion open for interpretation. This perspective article maintains that the capital theory approach to sustainability stands out as the most rigorous framework on the topic. The capital theory is a state-centric system of ideas where national governments oversee a portfolio of capital stocks of four families: natural capital, economic capital, human capital, and social capital. It is the duty of the government to act on the capital flow between different stocks to allow sustainable long-term development. This perspective paper underscores several envisaged gains from the application of the capital theory approach in public policy. Considering these expected gains, policy makers should be encouraged to experiment with the approach.