This paper explores the role of engaging teachers in constructive dialogue within ICT professional development activity. As part of an ICT professional development program, sixteen teachers across eight geographically removed schools participated in an online threaded discussion forum for a school year. Data reported in this paper are generated from the archived posts to a threaded discussion forum and are analysed qualitatively for evidence of community and quantitatively for different forums of feedback (Makitalo, Hakkinen, Leinonen, & Jarvela, 2002) and levels of discussion (Jarvela & Hakkinen, 2002). The findings suggest evidence of both collegial and critical forms of discussion. Collegial discussion was found to be important in developing and maintaining community while critical discussion was vital for its role in transforming teachers' beliefs. The data also revealed a number of practical aspects of online environments that inhibit what is termed in this paper as constructive discussion. (Contains 1 table and 16 figures.)