The purposes of this study were to explore the factors that motivated and those thatdiscouraged students from speaking English outside of the classroom at Asia-PacificInternational University, Mauk Lek Campus. The university offers undergraduate programsin both English and Thai medium. The majority of Thai students who were enrolled in bothprograms notably lived in the University dormitories, which exposed them to students from32 different countries, yet were still hesitant to speak English.Using the convenience sampling method, 197 students were selected to participate in thisstudy. A descriptive quantitative method and a self-administered questionnaire were used tocollect the data.The findings reveal that motivation for speaking English outside the classroom was mainlyfor instrumental motivational reasons (M=4.17, SD=0.59), followed by integrativemotivational reasons (M=3.74, SD=0.67). Less clear reasons were intrinsic motivation(M=3.41, SD=0.75) and extrinsic motivation (M=3.32, SD=0.82) motivations. The study alsoreported that factors such as inadequate vocabulary to speak effectively, insufficientknowledge of English grammar, and inability to speak English fluently and continuously,were perceived as hindering them from speaking English outside the classroom. Lastly, thestudy found statistically significant differences at the 0.05 level in instrumental motivation,intrinsic motivation, and extrinsic motivation when compared with gender, faculty, classstatus, program of study, and period of learning.The recommendations for future research threefold: to study learning approaches to a varietyof vocabularies which would enhance students‟ communication outside of the classroom; tostudy participants from other nationalities; and to use a larger sample using other types ofsampling and data collection methods.