To help in-service English teachers improve their teaching practices and pupils' learning opportunities through an enquiry-oriented and cooperative approach, the author carried out collaborative action research during a practicum in a teacher education course at a university in Hong Kong. This article describes how the collaborative research projects were designed and implemented during an 8-week practicum. Results of the action research show that the projects produced positive changes to students' learning and promoted teachers' development as English language professionals. (Contains 2 tables and 2 figures.)