Researchers have explored second language (L2) teachers' knowledge focusing not only on their prior language learning experience, previous L2 teacher education, and teaching practices, but also on specific curricular areas, such as teaching L2 grammar, teaching L2 reading, and teaching L2 writing. This line of research has contributed to L2 teacher education, particularly how to develop an effective knowledge base for teacher candidates. This study was conducted to investigate English as a foreign language (EFL) teachers' knowledge of vocabulary instruction. Specifically, employing three qualitative techniques for data collection (i.e., interviews, classroom observations, and stimulated recall), the study examined seven Chinese EFL university teachers' knowledge of vocabulary instruction from four dimensions: their beliefs about vocabulary learning, their understandings about vocabulary teaching, the relationship between their knowledge of vocabulary instruction and vocabulary teaching practices, and the sources of their knowledge about vocabulary instruction.