This paper explores how Hong Kong student teachers develop professional knowledge in learning to teach English as a Second Language (ESL). Three student teachers were tracked over the two years of their initial teacher education programme with data collected at periodic intervals during the programme in order to chart the development of their professional knowledge. Results show that although the student teachers underwent critical changes in their thinking and knowledge, these changes were not necessarily reflected in their classroom practice. This enquiry into the student teachers’ professional learning extends our understanding of the impact of initial teacher education on ESL student teachers’ thinking about language teaching and learning, and their development of pedagogical knowledge. Implications are drawn for developing second language teacher education programmes in the Hong Kong context.[Copyright © 2003 The Hong Kong Institute of Education.]