This paper addresses using social media to promote pre-service science teachers' practices of Socio-Scientific Issue (SSI) based teaching in a science classroom setting. We designed our research in two phases. The first phase examined pre-service science teachers' perceptions about using social media to promote their SSI-based teaching. The participants of this phase were 37 pre-service science teachers of universities at Bangkok who were going to complete practice teaching during a field experience course in the 2014 academic year. We collected data using a questionnaire and analyzed the results using descriptive statistics and content analysis. For the second phase, we mentored two students as they learned to use SSI-based teaching. These two individuals were our case studies for this paper. Throughout the mentoring processes, we collected data from their posts on social media, and then analyzed it using content analysis. The findings indicated that most pre-service science teachers perceived that communication through social media provided opportunities for posing questions and requesting clarification with the goal of developing their SSI-based teaching. Moreover, we found five strategies that were effective in terms of promoting pre-serviced science teachers' implementations of SSI-based teaching. These strategies included using various social media as a channel for giving feedback; providing empirical examples for pre-service science teachers' holistic views of SSI-based teaching; providing a friendly atmosphere to encourage reflection in order to identify and address challenges associated with SSI-based teaching; motivating the pre-service teachers to collaborate with a cooperative teacher or mentor about SSI-based teaching; and continually following up on their progress in SSI-based teaching. We considered these findings in terms of further online mentoring program design.