Teachers' professional development is a key factor in improving science education, but it shows limited impact when only a small number of teachers is reached, or when it focuses on only one aspect of teachers' development, such as learning science content, and is disconnected from teachers' practice. In order to increase the impact of our work on teachers' professional development, we implemented in 2007 ComPratica, an online network intended to establish a virtual community of practice involving biology teachers and biological education researchers. We present here the results of the first 2 years of this project, obtained through an analysis of the number and distribution of actions performed by the participants in the community, the kinds of activities in which they are engaged, and the themes addressed in their messages. From these data, we conclude that ComPratica is effectively functioning as a community of practice and is leading to changes related to both teachers' and researchers' professional development, which seem capable of reducing the research-practice gap in science education.