In this paper the lexical environment of secondary school English language classrooms in Hong Kong and Guangzhou are compared. Teacher output for one week of first-form lessons was recorded in two representative schools. Lexical richness in terms of type-token ratio and word-type frequency was measured, the words that were explicitly taught were identified and categorized according to whether the teaching was planned or unplanned, and the teaching treatments accorded to these words were examined. The lexical richness of teacher output was found to be greater in the Hong Kong classroom than in the Guangzhou classroom. In the Guangzhou classroom more words were explicitly taught, but learners were exposed to far fewer word types for incidental acquisition. In both classrooms, more unplanned than planned words were explicitly taught. Teachers tended to teach planned words through multiple treatments, with various kinds of input, both modified and unmodified, in different stages of the lesson. They provided almost no opportunities, however, for modified (negotiated) output on the part of the learners, despite the fact that the syllabuses in both Hong Kong and Guangzhou are described as ‘communicative’.