Social Media (SoMe) as a learning tool, though ubiquitous in society and popular within medical education, is often criticised as superficial. Its limitless output has been blamed for encouraging shorter attention spans and shirking in-depth reflection. The evidence base is itself superficial and lacking rigour or meaning. We aimed to consider a theoretical basis for how 'quality' learning may happen on such platforms. Our findings then informed the construction of a taxonomy for SoMe learning. We conducted a qualitative interview study of United Kingdom (UK) medical students using a theory-informed inductive study design. The research question was: 'How do medical students conceptualise quality of learning on social media?'. We purposively sampled participants from responses to a short survey collecting demographic and SoMe usage data. Interview data were analysed using framework analysis and informed by Blooms taxonomy, connectivism and communities of practice (CoP) theories. We received survey responses from 118 medical students across 25 UK medical schools. From these, 13 participants were recruited to individual semi-structured interviews. We constructed three themes through framework analysis of interview data: cognitive hacking, professional identity reflection and safety, control and capital. Quality SoMe learning may be conceptualised as a socially connected process, built upon constantly evolving networks but inexorably influenced by fluctuating hierarchy within learner-centric CoP. Educators and institutions may support high-quality learning for students through engagement which promotes community development, and safe, listening environments which foster professional identity formation.