This article explores how differences in individual plant performance affect species coexistence in communities. High-density environments favor species with high variation in performance, while low-density environments favor species with high average performance. When there is a trade-off between mean and variance in performance, stable coexistence can occur at intermediate densities. However, if one species is superior, intraspecific variation can blur differences between species. In real communities, intraspecific variation may not play a significant role in maintaining diversity.