Language teachers in China often use picturebooks as complimentary teaching materials to standard textbooks for language instruction. However, research shows that current applications of picturebooks in Chinese English as a foreign language (EFL) classrooms mainly focus on helping students develop linguistic competence, with little attention on students' meaning-making process. This study explored the use of picturebooks in an early elementary EFL class in China, with a particular focus on developing young EFL learners' communicative competence and helping them to gain more tacit knowledge about the world through picturebook use. Under the theoretical framework of language socialization and cultural-historical activity theory (CHAT), this study focused on language as a means of socialization alongside socialization as a means to learn language. Using data collected from classroom observations, recordings, interviews, focus group, and artifacts, this study analyzed students' learning processes with picturebooks through a CHAT framework and conversational analysis tools. This study found that both students and teacher used multiple semiotic resources related to picturebooks (e.g., images and texts) in terms of topic management, meaning making processes, first language (L1) socialization and repair practices. Moreover, there is a fluidity of power dynamics in this process, where students gradually took on various labors and used increasing numbers of tools to mediate their learning. The study also found that students gain knowledge about the world such as gender diversity, religious customs and virtues through picturebook use. This research finally proposed a seesaw model that emphasized students' agency in learning, and provided implications for EFL teachers and researchers in the language socialization field. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]