Using as reference the theoretical field of conflict resolution, this dissertation discusses the effects of security in wide peacekeeping operations. Based on an analysis of the elements of the internal security dilemma, this dissertation discusses the importance of consolidating the security in the post-Cold War peace operations held by the UN and the state-building process. The empirical studies reported in this work were both considered successful by the UN, having fulfilled their mandates with activities and programs developed in the security and socio-economic reconstruction arenas. The view expressed in this dissertation is that security, understood as the absence of militarized threats, is not enough to guarantee the completion of the mission: as wide peacekeeping deals with threats both in the military and the non-military arenas, it demands both material and non- material approaches, although the latter is not commonly studied by conflict-resolution researchers. Tackling structural violence and preserving cultural diversity has become essential for the success of wide peacekeeping. Failing to do this is to ignore the causes of the conflict, at the risk of seeing violence return. It is also necessary to count with the support of the international community, which is essential to the cooperation between parties. The dissertation concludes that wide peacekeeping is not aimed only at the resolution of the conflict, but rather intends to deal with its causes, treating each mission as unique in its particularities and limitations and preventing the conflict return.