Abstract: Mob justice remains a major public administration and governance challenge in Nigeria, reflecting weaknesses in formal security and justice institutions. This study examines the determinants of mob justice in Uromi, Edo State, focusing on community security structures, trust in state institutions, and state response mechanisms. It is anchored on Social Contract Theory and Procedural Justice Theory, which explain how institutional legitimacy and perceived fairness influence compliance with formal legal systems. A quantitative cross-sectional survey design was employed, involving 400 adult residents selected through stratified random sampling. Data were collected using structured questionnaires and analyzed using descriptive statistics and multiple regression analysis. The results show that community vigilante presence has a significant positive effect on mob justice (? = 0.48, t = 8.00, p < 0.001), while neighborhood watch effectiveness reduces mob justice (? = ?0.22, t = ?4.40, p = 0.001), with an explanatory power of R² = 0.52. Trust in the police (? = ?0.55, t = ?7.85, p < 0.001) and judiciary (? = ?0.41, t = ?6.83, p < 0.001) significantly reduce mob justice, explaining 61% of variation (R² = 0.61). Similarly, police response time increases mob justice (? = 0.44, t = 8.80, p < 0.001), while prosecution effectiveness reduces it (? = ?0.38, t = ?6.33, p < 0.001), with R² = 0.57. The study concludes that mob justice is strongly linked to governance deficits, institutional inefficiency, and weak public trust, rather than isolated criminal behavior. It reflects a breakdown in public administration effectiveness and the social contract between the state and citizens. The study recommends strengthening community policing, improving judicial efficiency, regulating vigilante groups, enhancing accountability, and promoting civic education to reinforce rule-of-law compliance. |