Based on the tenets of ethnolinguistic identity theory, this paper provides an insight into the complexity of ethnolinguistic identity and its relationship to ethnolinguistic vitality among young Finns with a Swedish-Finnish, mixed language family background. Questionnaire data was collected in Swedish language secondary schools in 2014 (N = 115). The data was analyzed with structural equation modelling. The results showed that ethnolinguistic identity may comprise affiliation with both Swedish and Finnish speakers as well as bilinguals. Further, higher subjective vitality of Finnish was significantly related to higher identification with Swedish speakers but it was not significantly connected to Finnish-speaking and bilingual identities. In parallel, higher subjective vitality of Swedish was significantly related to higher identification with Finnish speakers but it was not significantly related to Swedish-speaking and bilingual identities. Findings and their implications are discussed.