Western theories suggest that self-concept consistency is important for well-being, but cultural psychologists have proposed that this relationship may be weaker in collectivistic or dialectical cultures. Hypotheses regarding the ability of self-concept (cross-role) consistency and short-term stability to predict hedonic and eudaimonic well-being across cultures were tested. College students in the United States, Australia, Mexico, Venezuela, the Philippines, Malaysia, China, and Japan rated their traits in various roles at test and retest and completed measures of hedonic and eudaimonic well-being. In all cultures, cross-role consistency and short-term stability were inversely associated with negative affect, an aspect of hedonic well-being, and positively associated with Big Five Emotional Stability. In contrast, cross-role consistency and short-term stability were related to eudaimonic well-being more reliably in individualistic cultures than in collectivistic cultures, although the results in China only partially conformed to this pattern. We concluded that cross-role variability and short-term instability of self-concepts have a significant temperamental or affective basis, and this temperamental basis is a cultural universal. In addition, cultural psychology predictions of a weaker relationship between self-concept consistency and well-being in collectivistic cultures, as compared with individualistic cultures, were largely supported for eudaimonic well-being.