Opposition unity is often described as prerequisite of successful regime transitions. Particularly in presidential systems with plurality elections, the degree of opposition unity or fragmentation seems to go a long way to explain the success or failure of opposition parties. But when do opposition actors unite against the President and his ruling party? When are they able to surmount their internal tensions and coalesce in their democratizing battle against authoritarian rule? When does the anti-regime cleavage cancel out personal, ideological, and other differences? Or defining the puzzle the other way round: what explains the eventual failure of strategic coordination? Electoral rules (Cox), authoritarian divide et impera strategies, societal cleavages (class, ethnic, regional, ideological), or personal rivalries? And indeed, can such variables explain outcomes, or should opposition unity be viewed as endogenous, in which the likelihood of successful democratization helps to unite a fragmentary opposition. The paper investigates these issues with reference to Sub Saharan African case materials.