In this essay, I explore Alain Badiou’s longstanding project of theorizing political situations and political transformation through the analysis of forms and formalisms. This amounts, I argue, to a politics of form that draws on the thought of Sartre, Althusser, and Lacan, but offers new alternatives for political thought and action today. In particular, Badiou’s rigorous consideration of forms, which draws on mathematics, model theory, set theory, and category theory, allows him to theorize political change in a way that avoids the errors of existing critical approaches. Central to this consideration are Badiou’s theory (Being and Event) of what he calls the event, which summons itself into existence by its own naming of itself or auto-nomination, and his recent theory of the plurality of worlds and their possible transformation in Logics of Worlds. I also discuss Badiou’s recent treatment of the 20th century project of formalization in The Century, arguing that Badiou’s analysis here offers useful terms for the political thought of the present situation.