Abstract One of the fundamental challenges facing civil society organizations around the world is how to make democratic consolidation possible. While these organizations, in their various types and categories, in most countries of the world, continue to mediate and respond appropriately to emerging political imperatives, between the state and the individuals, civil society organizations’ effort towards the consolidation of democratic ideals in Nigeria appeared to be undefined, ambiguous and faced with certain challenges. To this end, the role of civil society organizations in democratic consolidation within 1999-2015 remained largely unclear. Consequently, this study examined the role of civil society in democratic consolidation in Nigeria within 1999- 2015. By means of descriptive survey and a content analysis designs, both primary and secondary data were elicited for the study. 4 popular Civil Society Organizations (8 in total), whose state branches cut across the 36 states of the federation, were purposively selected in both Anambra and Ebonyi states. Furthermore, 73 respondents were selected through an expert sampling procedure, while 31 journal articles, annual reports and other unpublished works that bordered on the research objective were content analyzed to complement the survey method used in the study. The reliability for the research instruments that were used in both designs employed in the study were tested using the Guttmann scale of coefficient of reproducibility and the Cohen’s kappa (k) symmetric measure of agreement between two independent coders. The results of the reliability test yielded 0.85 and 0.692 respectively and were considered very high. Following the analyses of the study’s objectives, it was discovered, among others, that civil society organisations had significantly played critical roles in election monitoring, advocacy for transparency and accountability and human rights campaign, while they had minimally or not at all engaged in democratic consolidation in Nigeria within 1999-2015. Consequent upon these findings, the researcher recommended, among others, that civil society organisations develop their local resource mobilization skills, including developing individual and community philanthropy techniques and building relations with local businesses and corporate social responsibility programmes.