The prime objective of this research was to investigate whether Facebook helped undergraduate students of Universiti Sains Islam Malaysia (USIM) improve their English language proficiency, critical thinking, comprehension skills, and motivation. A triangulation method (quantitative, qualitative, and descriptive) was employed in the investigation. A total of 900 undergraduate students participated. The 900 participants were first year students from USIM. The instruments used in this research were questionnaires, interviews, and observations. Results from a pre-test and a post-test showed that students who used Facebook i.e. the control group outperformed (88.8% passed) the students who were not exposed to Facebook (60% passed) in all the three categories. The findings indicated that Facebook indeed helped students to improve their English proficiency, besides learning new words and terminologies. This research offers guidelines to future researchers on the methodology of learning English language and helps them design an effective interactive multimedia learning environment in their classroom. The findings of this re- search would also contribute to the expansion of the paradigm of Constructivism. The findings of this empirical research could be prototyped for learning other languages in the classroom.