Though there is an urgent need to improve Thai graduates' ability to speak English fluently, very few studies have focused on students' fluency in language teaching in Thailand. The study investigated 86 third-year university students' beliefs regarding English-speaking fluency, including the characteristics and importance of fluency and the factors promoting and hindering students' English-speaking fluency. Through a mixed- methods design, i.e., a questionnaire, semi-structured interviews, and reflective journal entries, the results revealed that majority of the participants perceived fluency as referring to the flow of speech with few reasonable pauses. Most of them believed that fluency was important for speaking skills, that it enabled effective communication, that fluency should be prioritized over accuracy, and that those who could speak English fluently looked impressive. However, the findings showed different views among the student participants on whether accuracy can lead to fluency. Moreover, a large proportion of them still believed that speaking accurately was also important for effective communication. Interestingly, the findings also showed that some of the participants believed that fluency constituted a high rate of speech which is not supported by the literature. They believed that exposure to English, living in a good English environment, delayed corrective feedback from the teachers, using media, and participating in speaking activities could improve their English-speaking fluency. Contrastingly, individual affective factors including anxiety, lack of motivation and confidence, lack of linguistic knowledge, and immediate corrective feedback hindered their English-speaking fluency. The results also raise an awareness about Thai EFL university students' beliefs regarding English-speaking fluency for teachers, educators, students, curriculum designers, and material creators.