We investigated the role of sociocultural (between-groups) and individual (within-group) factors on the development of preschoolers' resource-allocation preferences. We tested claims of the "joint impact hypothesis" of social values development that social-emotional understanding skills would predict the transition from simpler (individualistic allocations) to more complex (cooperative, competitive allocations) social values and that cultural background would determine which values emerged. American children ages 37-67 months from Spanish-speaking Latino (n = 134), English-speaking Latino (n = 50), and English-speaking Caucasian (n = 98) backgrounds twice completed a resource-allocation task and a social-emotional understanding assessment, separated by 6 months. Contrary to predictions, results revealed that for no group were complex choice allocations more common at Time 2 than at Time 1. Moreover, for the Caucasian group, social-emotional understanding did not predict time-dependent choice allocation behavior. For Latinos, however, results revealed differential social values development according to language background. For Spanish-speaking Latinos, higher social-emotional understanding scores predicted emergent cooperative choices, and for English-speaking Latinos, higher scores predicted emergent competitive choices. Findings are consistent with differential socialization wherein social-emotional understanding skills facilitate the development of culturally mainstream values for more acculturated Latinos and ethnic cultural values for less acculturated Latinos.