The Chinese-Indonesian ethnic minority is one of the minorities in Indonesia with a long time history of being treated differently, for example the Kerusuhan 1998 (the 1998 riot). Because of this riot, this ethnic minority experienced trauma, held negative stereotypes against the majority, and now tend to avoid any unnecessary contact with the ethnic majority, causing a lower level of tolerance to the ethnic majority. Therefore, a study about tolerance in this ethnic minority is important, to increase better ethnic interaction between the minority and majority ethnicities. Previous studies have found the role of personal factors (i.e… empathy and personality) to influence the development of tolerance to diversity. This study is looking for another possibility in terms of external factors that can influence tolerance to diversity, since tolerance is something that can be taught and learnt. The one possibility is ethnic-racial socialization from parents. Therefore, this study looks the relationship between tolerance to diversity and ethnic-racial socialization in Chinese-Indonesian young adults (N = 208, age 19-30 years old); the age range, which has the strongest relationship for tolerance to diversity. Results showed a negative relationship of ethnic-racial socialization and tolerance. This finding suggests that perhaps the discrimination that they already experienced before could contribute something on the process of socialization. Future studies about ethnicracial socialization are still needed to analyze on how parents of Chinese-Indonesians develop their children's tolerance to diversity.