Given the "linguistically diverse population" of Kuwait (Tryzna & Al-Sharoufi, 2017, p. 79), English has become a "lingua franca" (Crystal, 2003) which facilitates communication among other non-native speakers in everyday life. Kuwait's Minister of Education (MOE) reports experiencing an English teacher shortage (Kuwait Times, 2019). Globally, teacher shortage has been an ongoing problem associated with low job satisfaction levels that lead teachers to quit (Green-Reese et al., 1991). Therefore, it is imperative to study the factors that impact English teachers' motivation-related outcomes (job satisfaction and their motivation to quit). An explanatory, sequential, mixed methods design was used to investigate the influence of competence beliefs (English language proficiency and teaching self-efficacy) and classroom goal structures (mastery and performance classroom approaches) on teacher motivation-related outcomes of 579 English teachers in Kuwait, a population largely overlooked in the literature. Phase I survey results revealed that classroom goal structures were the strongest predictor of teachers' job satisfaction, and efficacy in student engagement was found to be significantly related to teachers' job satisfaction. In Phase II, interviews were conducted with three highly-satisfied teachers about their experiences. Teachers in Kuwait revealed a list of mastery- and performance- related strategies, goals, and engagement methods they used which contributes to their high job satisfaction. This study presents a significant theoretical contribution to the literature and provides practical implications for professional development and teacher education programs. [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.]