Increasing attrition rates affect the quantity and quality of teacher human capital worldwide and pose threats to classroom practice and student learning outcomes. Understanding of these effects will be advanced by studying the reasons why preservice teachers leave or remain in the teaching profession. Literature indicates a range of influential factors contributing to preservice teachers' decisions to teach and vary across cultural contexts, particularly in studies using the FIT-Choice model. The policy and research context in Vietnam make it a fertile environment to examine motivational factors and differences influencing preservice teachers' perseverance within the teaching field. Most prior applicable studies employed either quantitative or qualitative approaches, thus limiting an integrated comprehensive picture. In contrast, this study employs an explanatory sequential mixed method design to identify different decisions made by preservice teachers approaching graduation, influential factors shaping their decisions, and how socio-cultural factors may differently impact sub-groups of participants. As few prior studies address the problem of preservice teacher attrition, this study adds to the current literature and should help policy makers and teacher trainers better support and prepare preservice teachers for their teaching career. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]