Digital communication has been focus of discussion in the last decades. Although schools are expected to follow this trend, they face big challenges for using or implementing new technologies. This study involved the use of Facebook for educational purposes, as a collaborative online space for enabling communication among teachers from different schools. The article describes how a group on Facebook of 43 secondary education teachers, from different schools in the southeast region of Brazil used Facebook as a collaborative space for communicating among each other. On Facebook, these teachers shared experiences about the use of digital technologies in their high school classes. This study is based on Cultural Historical Activity Theory (Leontiev, 1978; Vygotsky, 1997), and follows the methodology of Critical Collaborative Research (Magalhães, 1998). The objective of this study is to explore how teachers developed collaboration with each other on Facebook, and to understand the impacts of using the groups in the broader communities. We examined the posts on that group from 2012 to 2014, where teachers and the researcher could make posts or comments. Our findings suggest that teachers tend to critically collaborate in smaller groups and that the use of online groups can enable schools to endorse its use, combined with face-to-face meetings.