Language becomes an important intergroup category for children from early on in their lives; however, few studies have examined the role language plays in social inclusion and exclusion. This study examines how adolescents and emerging adults in China make inclusion judgments of language-outgroup members and what reasons they use to justify their inclusion judgments. High school and university students (N = 376, 63.3% female) were recruited to complete a survey designed to examine their inclusion judgments and justifications. Our findings indicate that participants made different inclusion judgments toward speakers of different languages, and language was the most frequently used justification. They also used group identity, personal choice, and autonomy, group functioning, nationality, moral, and political/historical reasons as justifications. Adolescents were found to be more exclusive than emerging adults and used group identity and political/historical reasons more often to justify their inclusion judgments. The findings add to our understanding of the sophisticated ways in which adolescents and emerging adults make social decisions.