With the trend toward globalization and the continual change of the ethnic composition of the U.S. population, there is increasing awareness in the U.S. that not every child is raised in an English-only family. The purpose of this research is to explore the relationships among heritage language proficiency, ethnic identity, and self-esteem in the American-born Chinese (ABC) children who go to Chinese language schools for Chinese language learning on weekends. A total of 63 students and their 56 parents are surveyed in the quantitative study. Results show that there are positive relationships between Chinese heritage language proficiency and ethnic identity (r = 0.316, p = 0.006), language proficiency and self-esteem (r = 0.255, p = 0.022), and ethnic identity and self-esteem (r = 0.240, p = 0.029). The study provides implications for the Chinese language schools, parents, educators, and policymakers, as well as the implications for future study.