This study proposed that captioned television, as a multi-sensory, largely entertaining medium might be an important source of comprehensive input for bilingual students in learning language and literacy. To explore this issue, the study investigated the following questions: (1) can bilingual students acquire vocabulary incidentally through watching closed-captioned television?; (2) if specific effects are found, are there certain word-related and video-related variables that contribute to these vocabulary gains?; and (3) what is the relationship between students' linguistic proficiency in English and their learning of vocabulary through comprehensible input? One hundred and twenty-nine bilingual seventh and eighth graders from 17 science classrooms in a middle school participated in the 12-week study. Classrooms were randomly assigned in one of four groups: (1) captioned television; (2) television viewing alone; (3) reading along and listening to text; and (4) text book only. Results of the study provide strong support for the effects of captioned television on bilingual students' acquisition of language, literacy, and conceptual knowledge. Captioning presented a particularly rich language environment that enabled students to incidentally learn words through context as they developed concepts in science. Overall, the study demonstrated the power of captioned television to provide comprehensible input to language minority students. The appendix provides a script and narrative from a science program, with target words underlined. (43 references) (JL)