Whereas there has been some research on the role of bottom-up and top-down processing in the learning of a second or foreign language, very little attention has been given to bottom-up and top-down instructional approaches to language teaching. The research reported here used a quasi-experimental design to assess the relative effectiveness of two modes of academic English vocabulary instruction, bottom-up and top-down, to Chinese university students (N = 120). The participants, divided into two groups-bottom-up and top-down-were exposed to 48 hours of explicit vocabulary instruction. Their achievement was measured with two vocabulary tests, Academic Vocabulary Size and Controlled Productive Knowledge, administered at the start (T1) and at the end (T2) of the treatment. Analyses of the test scores reveal that at T2 the bottom-up group slightly outperformed the top-down one on both vocabulary size and controlled productive knowledge. With respect to the former, the bottom-up group's superiority was found to be statistically significant, although with a relatively small effect size (g 2 = .05).doi: 10.1002/tesq.170 B ottom-up and top-down processing are well-established concepts in a wide range of fields, including psychology, cognitive science, pedagogy, and institutional management. They refer to two essentially different ways of processing and/or organising information. Broadly speaking, bottom-up is a form of inductive (or data-driven) processing starting with smaller and/or lower-ranked units and moving upwards through larger and/or higher-ranked units. Top-down is a form of deductive (or schemata-driven) processing working in the opposite TESOL QUARTERLY Vol. 0, No. 0, xxxx 2014