This paper explores the evolution of Social Media Critical Discourse Studies (SM-CDS) and, in this context, outlines four essential approaches for critical research on social media and the underlying communicative paradigm. Thus, the paper adds to existing research in two ways. First, it provides a conceptualisation and visualisation that integrates Digital Discourse Analysis, Critical Discourse Studies, and the critical discourse-analytical study of social media. Second, taking this as a springboard, the paper proposes a classification scheme for past and future critical research on social media. The paper argues that critical discourse-analytical work should encompass at least four approaches: (1) using social media as repositories of data, (2) contextualising and theorising social media, focusing on (3) discourse produced by social media providers and (4) discourse about social media. In addition to discussing the scope of each approach, the paper elucidates their epistemological value. Overall, the article finds that critical engagement with social media has predominantly focused only on two of these approaches, highlighting the importance of expanding existing social media research with an eye to the additional key approaches identified.