This paper explores some potentials and issues of fostering learning communities through Computer-Supported Collaborative Learning (CSCL) technology in Singapore classrooms. The subjects were eight teachers who attended a professional development course conducted at the National Institute of Education. The course focused on preparing teachers in integrating information technology into teaching and learning. CSCL, in particular, Knowledge Forum®, was adopted as a platform for online discussion and knowledge building on these technology integration issues. Interviews with these teachers and analysis of their online discussion suggest that they appreciate the knowledge building approach as a means for the students and themselves to learn beyond classroom and in promoting in-depth learning. However, the teachers felt that the approach was time consuming and was more suitable for high-ability students.