This study explores the evolution of student-led social networking groups initiated and sustained by a cohort of undergraduate students over a 3-year time frame. The study contributes to this growing area of research by exploring the impact of peer-led, peer-supported informal learning through social media networks. Social capital is a useful lens through which to understand the findings, and particularly in interpreting descriptions of the evolution of the group over time. The findings suggest that students build bridging social capital to support the transition into higher education, form relationships and learn collaboratively through a large cohort-based Facebook group. Over time, this form of social capital and the use of the Facebook group declines due to a lack of perceived reciprocity and an increased perception of competitiveness amongst peers. However, there is accompanied by a subsequent rise in the building of bonding social capital between closer peer relationships facilitated through the use of various WhatsApp groups. The findings have implications for considering how social networking might support the student journey towards more nuanced, more personalised collaborative learning and a move towards more self-directed learning.