This chapter engages herder-farmer conflicts in Nasarawa state, Nigeria, with emphasis on trends, manifestations, actors, causes, management, consequences and critical lessons for security, development and peacebuilding. While the problem is longstanding, it has assumed changing form and character in contemporary times, with negative consequences: national and human security, deaths, displacements, and loss of livelihood; and gender implications for women - rape, assaults, loss of pregnancy and miscarriages by women in IDP camps. Many factors explain the conflicts, notably environmental scarcity, migration and competition for scarce natural resources and the poor management of the conflicts by both state and non-state actors. The inability to effectively manage the conflicts is not unconnected to factors such as the reliance on poor regulatory frameworks, dominance of state and the marginalization of non-state actors, political interference and politicisation, corruption and extortions of the locals by security agents, and failure to act proactively using early warning signals/reports, leading to late deployment of security personnel. Sustainable peacebuilding requires redressing these shortcomings through collaboration between state and non-state actors, prompt deployment of security agents based on early warning reports, avoiding premature withdrawal or reduction in the number of security agents deployed for peacekeeping in conflict affected areas, better management of returnees and IDP camps, demilitarization and continuous peace education.