The Republic of South Sudan is a multi-ethnic sovereign entity, consisting of 10 states and comprising a culturally diverse population. While this ethnic diversity speaks to the country's rich national heritage, it has also always been a source of internal ethnic discord in South Sudan. Since South Sudan gained independence on 9 July 2011, the country has witnessed localised inter-ethnic conflicts, most notably arising from disputes rooted in grazing land, cattle raiding and access to natural resources - predominately in Jonglei State of Greater Upper Nile Province. Despite multiple, concerted and ongoing national and local efforts to address the security challenges arising from ethnotribal disagreements, this phenomenon still persists and renders the overall situation rather fragile. This article seeks to examine the impact of ethnic conflicts on peace efforts in South Sudan. It argues that the seething inter-ethnic clashes are serious constraints and a source of threat that stands to obfuscate South Sudan's successful transition to sustainable and effective post-conflict recovery and long-term peacebuilding.