The paper examined regional integration and the diversification of the Economic Community of West African State economy (ECOWAS). The basic objective of establishing ECOWAS in 1975 as a regional block was to promote trade among member nations. But this basic has not been fully achieved as empirical facts suggested that fundamental challenges such one product economy and political differences. In order to address these challenges and put the ECOWAS economy on the path of development, the study used library science method to analyze this study. This was done by collecting data from secondary materials on regional economic integration in ECOWAS and other regional blocs. The content analysis showed that one of the challenges of ECOWAS nations that inhibit her development is lack of economic diversification. Thus, the region needs to diversify her economy from one product economy through her productive sectors in order to compete with favourably with other regional power blocks in term of trade. Based on the finding above it was suggested that, the ECOWAS government must strive to address the unsettled issues of economic diversification by moving away from been a consumption economy to production economy.