This study will examine political party systems, with particular emphasis on the impact of ethnicity on party formation in both Nigeria (1951-1961) and Sierra Leone (1950-1967). Particularly in terms of this study, the hypothesis will be advanced that in countries as ethnically divided as Nigeria and Sierra Leone, political parties formed from a nucleus of members from one or another subsystem, such as an ethnic group, which engage in competitive elections will create sectional and ethnic tensions. The major finding of the study, is that a country or countries with sharp ethnic-cleavages, will tend to produce a multi-party system unless there are intervening factors to mitigate against such party-formation. / Arts, Faculty of / Political Science, Department of / Graduate