Over the last few years, there has been an increased interest in how social network sites (SNS) particularly Facebook, could be used for educational purposes. Facebook has been used in the teaching and learning of various subjects but to date there is a dearth of studies on the use of Facebook as an informal platform to support the learning of English asa second language (ESL). This study investigates how Facebook could be used as an alternative platform to support students in learning English in a Malaysian higher educational institution. It is based on the premise that learning is a social process which involves interaction between learners and their 'more knowledgeable others', mediated by tools and artefacts in a community of learning. As such, this study is informed by the Sociocultural Theory (Vygotsky, 1978), the Community of Practice (Lave & Wenger, 1991), and the Community of Inquiry (Garrison et al., 2000). This study seeks answers to the following questions: 1) How did the teachers use Facebook group to support students in learning English?, 2) How did the students use Facebook group as an informal platform to learn English?, 3) How has the use of Facebook group influenced teachers' and students' English language teaching and learning practices? An action research project was conducted for 16 weeks at a Malaysian polytechnic, and it involved a class of first-year Civil Engineering Diploma students, their English language lecturer, as well as the practitioner-researcher. A Facebook group was created to support students in learning the AE 101 Communicative English subject in particular, and English in general. In line with the constructivist paradigm, the perspectives of participants involved were obtained through the analysis of Facebook wall posts, teacher and practitioner-researcher conversations, face-to-face and online interviews, researcher's diary, students' logbooks and ad-hoc questionnaires. Data was processed using Nvivo10, and then coded and analyzed using thematic analysis. Key findings revealed that the Facebook group was used as: a depository for learning materials, a forum for discussing academic as well as leisure matters, a social space to build and mediate relationships between members, and a psychological space to mediate their identities. In view of students engagement in social networking, this research proposes 'Social Netlearning' (SNL) as a way to embed learning into social networking platforms appropriated for educational purposes, and 'Discourse of Errors' (DoE) as the factor that should be capitalized by English teachers when using social networking platforms for ESL learning.