This study focuses on using wikis as a learning environment, as part of a professional development program for chemistry teacher leaders. The study was performed in Israel and involved 20 chemistry teachers. One goal was to investigate how using wiki may promote effective science teacher professional development. Various aspects of the teachers' wiki experience were investigated. Based on their contribution rate to the wiki activity, different participation profiles were revealed: 44% of the teachers were defined as peripheral members of the community, 28% as central members, and 28% as leaders of this community. Differences were observed between younger (below the median age of 45) and older teachers regarding their attitudes, feelings of ownership and preferences of working environment. The current study sheds light on the reasons why some teachers were more reluctant and less active in the wiki environment--the findings suggest that it is neither correlated with technical difficulties, nor with the relevance of the content. We believe that it has to do with the perception of the relevance of the wiki environment itself (as a model of other virtual environments) to their teaching in classroom. Small-scale results suggest a correlation between the teachers' personal participation rate in the wiki environment and their perception of their classroom as "student-centered" or "teacher controlled."