This mixed methods study aims to investigate the effect of readers theater, a drama-based activity whether it could help enhance preservice English teachers' English pronunciation as well as reduce their anxiety when pronouncing English. The participants (N = 49) were sophomores majoring in the English of Education program, who enrolled in a Phonetics and Phonology for Teachers of English course in the academic year 2020 in Thailand. Data were synchronously collected quantitatively and qualitatively. Regarding the quantitative research phase, the quasi-experimental design was specifically used to explore the effects of readers theater in the improvement of the participants' English pronunciation, particularly on two segmental features (i.e., /l/ and /r/). The participants were randomly divided into the control group (n = 26) and the experimental group (n = 23). While readers theater was implemented to the experimental group for one hour a week over 12 weeks, the control group received a traditional teaching method. The pre-test and post-test were administered to both groups before and after intervention. The speech perception was assessed using minimal pairs. The sound production assessment consisted of picture naming and interviews in a spontaneous speech setting. Five English native speakers judged the participants' voice recordings. Generally, the data from statistical analysis indicated that the participants in the experimental group made significant gain in the sound perception test (p < 0.05) with a large effect size (d > 0.8), while there was no significant difference found in the sound production test between either group. In a qualitative phase, three different sources of data were collected from the online survey, open-ended questions, and an anecdotal record from the experimental group after the 12 weeks of intervention. In general, most of the participants perceived that readers theater is a fun activity. They enjoyed reading scripts with peers, which helped motivate them to practice and gain more confidence when pronouncing English words. Overall, the primary results from this study suggested that readers theater could be used as an effective teaching tool to engage and improve Thai preservice English teachers' English pronunciation and prepare them prior to teaching in their own classrooms. [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.]