Whether emotion is universal or social is a recurrent issue in the history of emotion study among psychologists. Some researchers view emotion as a universal construct, and that a large part of emotional experience is biologically based. However, emotion is not only biologically determined, but is also influenced by the environment. Therefore, cultural differences exist in some aspects of emotions, one such important aspect of emotion being emotional arousal level. All affective states are systematically represented as two bipolar dimensions, valence and arousal. Arousal level of actual and ideal emotions has consistently been found to have cross-cultural differences. In Western or individualist culture, high arousal emotions are valued and promoted more than low arousal emotions. Moreover, Westerners experience high arousal emotions more than low arousal emotions. By contrast, in Eastern or collectivist culture, low arousal emotions are valued more than high arousal emotions. Moreover, people in the East actually experience and prefer to experience low arousal emotions more than high arousal emotions. Mechanism of these cross-cultural differences and implications are also discussed.