We estimate a finite mixture model in which countries are sorted into groups based on the similarity of the conditional distributions of their growth rates. We strongly reject the hypothesis that all countries follow a common growth process in favor of a model in which there are four classes of countries, each with its own distinct growth process. Group membership does not conform to the usual categories used to control for parameter heterogeneity such as region or income. However, the growth processes we do identify correspond to a significant degree with established theories of economic growth. The behavior of one group is broadly consistent with the neoclassical model, the behavior of two of the groups are consistent with two different endogenous growth models, and results for the fourth group are consistent with a model in which growth is difficult due to random shocks. Overall, these results suggest that existing theories of growth may be complementary rather than competing. Furthermore, the findings of a typical cross-country growth regression may be misleading because they do not accurately reflect the experience of any particular group of countries.