The objective of the study was to assess the effect of advocacy and campaigns on peace-building and conflict prevention in Sierra Leone. The descriptive survey involving the use of questionnaires was used to obtain data from the respondents. The sample size was one hundred and twenty (120). Both purposive and stratified sampling techniques were used in the study. The Statistical Product and Service Solutions were used to process the data. The data analysis involved the use of percentages, pie charts, bar charts and means. The study established that 93%of the respondents are of the view that Civil Society Organisations play a major role in consolidating peace-building in Sierra Leone. An appreciable proportion of the respondents stated Advocacy, Protection, Monitoring, and social cohesion as the major roles played by Civil Society Organisations in consolidating the peace-building process in Sierra Leone. The study revealed that Advocacy has a very high impact on the peace-buildingprocess in Sierra Leone. The study also established that the roles of Civil Society Organisations have helped in calling for the respect of human rights, promoting social justice &promoting gender equality