Teachers are highly influenced by their cognitions related to their ideas, to their views of the world, and to their values and conceptions of their environment. The study of teachers’ cognitions forms a part of the process of understanding how teachers conceptualize their work (Hassankiadeh, 2012). Therefore, this study attempted to investigate the cognitions the Indonesian EFL teachers hold about vocabulary instruction along with analyzing reflected cognitions in their teaching practices in classroom context. This qualitative study used semi-structured interview and direct classroom observation to obtain the data from four Indonesian EFL teachers of senior high school. It was revealed that the teachers have well-developed cognitions about EFL vocabulary instruction. It is shown from their beliefs, understanding, and perceptions about the role of vocabulary, its importance in EFL teaching and learning including what words are taught and how words are taught. Moreover, some aspects of their cognitions about vocabulary teaching emerge to be in congruence with their vocabulary teaching practices although some inconsistencies have been identified as well.