This study examined the impact of conflict management approaches on administrative effectiveness in tertiary institutions in Cross River State, Nigeria, with implications for peace and conflict management. The research involved 309 heads of departments and utilised an ex-post-facto design. The study employed a multi-stage sampling technique and a proportionate stratified random sampling method. A validated instrument, Conflict Management Approaches as Determinants of Administrative Effectiveness Questionnaire (CMSAEQ), was used to measure collaboration and mediation strategies. Data analysis using simple and multiple linear regression revealed that both collaboration and mediation strategies significantly influenced administrative effectiveness. The study recommended that conflicts should be effectively managed rather than ignored.