Introduction: Nowadays, one of the most important questions in teaching and learning involves increasing the degree of students' engagement in learning. According to Astin's Theory of Student engagement, the best learning environment is one in which it is possible to increase students' engagement. The current study investigates the influences that using these networks for educational purposes may have on learners' engagement, motivation, and learning. Results: By a detailed comparison of a control group using face to face education and an experimental group using the social network Facebook, this study found significant differences between the two groups in terms of learning, engagement and motivation. The Facebook group showed higher outcomes in the TOEFL post-test than the face to face group with no differences in the pre-test. The Facebook group report significantly higher levels of engagement and motivation after the course than the face to face group. Conclusion: Engagement was related to learning outcomes in the Facebook group, but not in the face to face group. Also the results of the Facebook group supported Astin's theory (the fourth principle: 'Development is proportional to quantity and quality of involvement' and fifth principle 'The effectiveness of any educational practice is directly related to the ability of that practice to increase student engagement'). No correlation between engagement and motivation was found. The discussion focuses on the role of engagement in learning.