This chapter proposes that social movements are sites for the production of a distinct kind of theoretical knowledge, namely insurgent social theory. This argument is anchored in the claim that subaltern groups have always and everywhere been involved in the production of theory. More specifically, social movements are animated by a form of knowledge production that is grounded in subaltern experiences of exploitation and oppression and oriented towards bringing about emancipatory transformation. The chapter begins by discussing the relationship between activism, experience, and insurgent social theory, and then outlines and discusses the basic features of insurgent social theory as a distinctive form of knowledge. The chapter’s final section reflects on how we should conduct our discussions of what different forms of insurgent social theory enable us to know and do and argues for a commitment to insurgent epistemic gain—that is, a form of engagement committed to producing theoretical knowledge that is more effective in advancing oppositional collective action towards emancipation.