This study examined the influence of children's emotion situation knowledge (EK) on their autobiographical memory ability at both group and individual levels. Native Chinese, Chinese immigrant, and European American 3-year-old children participated (N = 189). During a home visit, children recounted 2 personal memories of recent, 1-time events with a researcher. Their EK was assessed in a production task (children described situations likely to provoke happy, sad, fearful, or angry emotions) and a judgment task (children judged what emotions story characters were most likely to feel in various situations). European American children had higher EK scores and remembered more details of the past events than their Chinese peers, independent of the influences of age and language skills. EK had the strongest influence on memory reports and mediated the effects of other individual (age, language skills) and group factors (culture, gender). Findings are discussed in light of EK as an important mechanism for the development of autobiographical memory. (Contains 2 figures and 3 tables.)