Competitive exclusion can be classified as deterministic or as historically contingent. While competitive exclusion is the norm in nature, it has remained unclear when multispecies communities should be dominated by deterministic or contingent exclusion. Here, we provide a general theoretical approach to explain both the emergence and sources of competitive exclusion in multispecies communities. We illustrate our approach on an empirical competition system between annual and perennial plant species. First, we find that the life-history of perennial species increases the probability of observing contingent exclusion by increasing their effective intrinsic growth rates. Second, we find a shift from contingent exclusion to dominance with increasing numbers of competing species. Third, we find that the probability of observing contingent exclusion increases with weaker intraspecific competition, and not by the level of hierarchical competition. Our work provides a framework to increase our understanding about the predictability of species survival in multispecies communities.