This paper reports on the first results of an ongoing project whose aim is to evaluate whether a wiki-based knowledge sharing tool like TWiki facilitates effective processes of knowledge building, sharing and transfer and fosters collaboration in a community of practice made up of Italian teachers. The project started in October 2004 and first data were collected five months later. The project was an attempt to provide them the opportunity to build more productive working relationships, stimulate new ideas, take advantage from the sharing of the broad range of professional knowledge and expertise that resides within the school. We chose TWiki as collaborative environment because its features met our needs quite well: it is open, free, easy to customize, has a versioning system and does not use proprietary technology.