We examined the importance of parental culture maintenance behaviour, bilingualism, ethnic identity, and national identity for the well-being of adolescents in multicultural Indonesia. We tested a mediation model in which the link between (perceived) parental culture maintenance behaviour and well-being is mediated through speaking Bahasa at home and national identity on the one hand and speaking the ethnic language at home and ethnic identity on the other hand. Participants were 448 adolescents (261 females) from four Indonesian ethnic groups (Chinese from Java, Chinese from North Sumatra, Batak, and Javanese), aged between 12 and 19 years (Mage = 15.92 years). We found support that parental culture maintenance was positively related to both ethnic and national identity, was correlated to the usage of ethnic language at home, but not correlated to usage of Bahasa Indonesia at home, language usage was not associated with identity; there was no link between parental culture maintenance behaviour and usage of languages at home with well-being, but both national and ethnic identity were positively associated with children’s well-being across groups. We conclude that parental culture maintenance, ethnic identity, and national identity are important for the well-being of adolescents, whereas speaking the language is independent from well-being and ethnic identity.