The present study delves into the effect of incidental vocabulary on oral fluency development. Students with good vocabulary can present their ideas and thoughts with greater clarity. It enhances their fluency too. On the other hand, students with limited vocabulary in their arsenal often get stuck up halfway and look for instant help in the form of vocabulary closest in meaning to convey their ideas. Oral fluency is not a fundamental issue where a student either has it or doesn't. Instead, fluency is a matter of degrees. Hence, some degrees of fluency can probably be attained at all levels of ability. Vocabulary is an essential component of language, and it is closely related to listening and speaking. Given this state of affairs, students should gradually be acquainted with the linguistic tools, choices, and strategies they will need to communicate fluently, regardless of the level of language proficiency they may have at the moment. According to Brumfit (1984, p.56), fluency is "to be regarded as natural language use.”. Richards, Platt, and Weber (1985, p.108) define fluency as “the features which give a speech the qualities of being natural and normal, including native-like use of pausing, rhythm, intonation, stress, rate of speaking, and use of interjections and interruptions”. Vocabulary learning is also one of the most critical goals in first and second language classrooms (Nation Webb & Nation, 2017). Considering the vast number of vocabulary items in languages and the limited studies that have investigated incidental learning of words through listening and reading comprehension for enhancing oral fluency, researchers in this study will deliberately create incidental vocabulary learning environment, encourage students to make errors, create varieties of opportunities for students to participate in thought provoking vocabulary practice, developing activities that force students to focus on getting their message across. Level three EFL students enrolled at KKU, Faculty of Languages and Translation will be selected as control and experimented ones; after suitable training, Pre-test & Post-test techniques will be used to test the effect. The VLT (Webb, Sasao, &Ballance, 2017) will be administered in a paper and pencil format to determine their prior and after training vocabulary development. Participating students will be asked to answer a set of questionnaire related to oral fluency enhancement