The increase in globalization has boosted the widespread movement of ESL/EFL teachers across and within national borders. Teacher trainees from mainland China seek admissions into the United States (U.S.)-based second language (L2) teacher education programs, such as Teaching English to Speakers of Other Languages (TESOL) programs, as the first step in their academic and professional journeys as English teachers. According to the Open Doors Report, tens of thousands of Chinese teacher trainees enroll in TESOL programs in the U.S. every year. Most of these trainees will return to China and assume positions as ESL/EFL teachers. How such training processes in these TESOL programs affect teacher trainees' professional identity and result in different teaching behaviors could be significant, and thus requires in-depth investigation. The purpose of this study is to examine the professional identity formation of eight Chinese teacher trainees in a foreign and second language teacher education program during an essential stage of developing their self-perception as English language teaching (ELT) professionals. This study hypothesized that the findings and conclusions would: 1) provide information to help the next-generation ESL teachers transition to the teaching contexts in China, especially in the early steps of building fundamentals for their future career trajectories in becoming an ESL teacher, 2) reveal valuable linguistic and cultural resources for English learners, 3) provide valuable insights and information for both local and international teacher educators, as well as for institutional administrators, and policymakers to enhance English language education quality in both the United States and mainland China, 4) keep pace with the international development in the era of globalization, and 5) shed light on future investigations of the professional identity formation of Chinese teachers. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]