While over the past decade social network sites have enabled both learners and teachers to set up various forms of online collaborative learning environments, there is an ongoing discussion on how collaboration through these social media platforms can be situated with regard to the development of metacognitive awareness (Li, Pow & Chueng, 2015). This paper presents a study on the development of metacognitive awareness of first-year English majors collaborating in a closed Facebook group. The theoretical framework for the development of metacognition, proposed by Gunawardena et al. (2009), was used to analyse the students’ metacognitive strategies when working together online. The study shows that students utilise the social network site to complete given learning tasks, and extend their use of the forum by setting new learning goals and socialising with their peers. The students show that, through peer collaboration, they are able to evaluate and plan their learning process online.