Peacekeeping is a means by which international or regional organizations control conflict situations that are likely to endanger international peace and security. Most scholars have viewed the contributions of peacekeeping forces only in terms of failures, and they have not investigated fully the political-military circumstances" under which conflict control measures succeed. This dissertation is an attempt to bridge this gap and to show how the OAU compares with the UN in carrying out peacekeeping missions. The method of research was the case study method in which primary and secondary data was used to describe the situations in which six peacekeeping forces operated. The content of resolutions, official reports and secondary data were examined for non-trivial evidences of impediments to implementation of mandates. Findings from the research indicate that peacekeeping missions not properly backed by political efforts at settlement of disputes, cooperation of the superpowers, and financial and logistic support were ineffective and usually unsuccessful. Lack of consensus and pursuit of national interests have resulted in ambiguous or unrealistic mandates and have reduced the effectiveness of peacekeeping operations. Moreover, parties to a conflict were interested only in solutions that favored their interests and were often skeptical about the role and credibility of peacekeeping forces. But the continued violations of ceasefire agreements in defiance of the presence of peacekeeping forces were due partly to the force's inability to use force except in self-defense , Most of the forces operated under serious operational and logistical difficulties and they were inadequately funded. But none of the three factors has been responsible alone for the failure of peacekeeping missions. The coordination of UN operations has been better than that of the OAU. In civil war situations, national governments have requested peacekeeping forces because they could not, unaided, put down their opponents. The UN has deployed its forces only as a means of relaxing tensions while member-states have pursued other interests.