Mentoring, a main constituent of teacher education, has taken new shape in recent years, with educators incorporating technology and social media into their practices. This study investigated the use of a Facebook group as a form of informal mentoring among teachers with reference to qualitative and quantitative data collected from the entries, responses and comments of group members. Findings included a list of mentoring topics along with the number of comments and words for each entry. In this way, we were able to analyse quantitatively the contents of each mentoring topic and provide as qualitative evidence clear examples from member comments and exchanges. The findings revealed that EFL teachers shared experiences and knowledge on various topics such as pedagogical knowledge, pedagogical content knowledge, content knowledge, resources and career development.