This article uses Robinson’s nine types of national interest to analyse the state-building process of South Sudan since independence in 2011 comprehensively. The paper documents the number of substantial challenges the young state has met: widespread governance deficits; internal conflict; weak institutions; and entrenched ethnic and regional divisions have continuously impeded its move to long-term stability and development. The framework used by Robinson is also useful in this approach as it is systematic and distinguishes between primary (state survival, national unity), secondary (regional influence and alliances), permanent (sovereignty, territorial integrity, national identity), and variable (economic and political priorities) interests. This typology provides an apt frame of reference for South Sudan, emphasizing how competing and usually conflicting interests and external pressures influence state behaviour in a precarious post-conflict landscape. Its application demonstrates that unresolved contrasting interests, particularly those stoked by tribalism and ethno-nationalism, irrevocably disempower the state, thereby reinforcing its continued fragility. Tribal allegiances play a vital role in distorting national interest composition, prioritising ethnic loyalty at the expense of a unified national identity, generating factionalism at the expense of good governance and leading to an uneven sharing of resources. The paper emphasizes the significance of establishing durable and inclusive institutions that transcend ethnic boundaries when it comes to preventing social divisions and conflicts in perpetuity. What remains to be seen is whether the basic questions of sovereignty, ethnic identity, and controlling resources will be addressed through inclusive governance, systemic reform, or by developing shared national and regional goals in order for South Sudan to lift out of cycles of fragility and attain sustainable state-building.