Reflective practice is extensively discussed in the field of teacher education, and it is rapidly increasing in the field of teaching English to speakers of other languages (TESOL). However, reflective practice is still underrepresented in the literature of English as a foreign language (EFL) instruction. The purpose of this study is to understand ways, affordances, and constraints of reflective practice among postsecondary EFL instructors in the preparatory-year program (PYP) at King Abdulaziz University in Jeddah, Saudi Arabia. Cultural-historical activity theory (CHAT) was adopted as a theoretical framework that undergirds a qualitative case study design and thematic analysis. Data was purposefully collected from five experienced postsecondary EFL instructors through a series of semistructured interviews, classroom observations, and document reviews. It was found that instructors engage in diverse ways of reflective practice inside the classroom using intuitive, dialogic and translingual actions. However, they engage in limited ways outside the classroom using online surveys and formal professional meetings. Instructors' long teaching experience, sociocultural awareness, and reconceptualization were major affordances for instructors to engage in reflective practice. Course reports and technical PD were major constraints that limit instructors' engagement in reflective practice. CHAT was an effective framework to analyze reflective practice in the bound system of the PYP. This study contributes to add knowledge about reflective practice in the literature of TESOL and applied linguistics and fills a methodological gap using CHAT as a framework. The findings of this study provide practical and research implications for postsecondary EFL education in Saudi Arabia and TESOL programs in general. [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.]