Social media Facebook is now used by millions of people all around the world. Indonesia itself has become the biggest four of facebook users after the United States, Brazil, and India. This big number of users has made facebook the most popular platforms for online social networking among youth, and university students (Petrovic, at al. 2012). Facebook has a number of features as groups, instant messaging, video and picture posts, downloadable application etc. that can potentially be exploited by teachers and students to support and facilitate learning. This research was aimed at exploring those potentials especially in stimulating more teacher-students and students - students interactions. It was conducted at College of Languages of Sultan Agung Islamic University Semarang. The subjects were the students taking the course of the Introduction to Second Language Acquisition in the even semester of 2011/2012. In addition to classroom learning, the teacher created a facebook group and other applications for the course and added all the students as members so that he and the students were connected to each other. Topics for discussions to stimulate interactions between the teacher and the students as well as between students and students were posted. The students responded to questions, gave comments, even asked for materials (reading resources and references) to the group members. These activities were observed, categorized and analyzed. The analysis proves that facebook can be used to stimulate more interactions between the teacher and students as well as the students and the students.