This study examines the conditions of political intelligibility for popular assembly. What are the normative constraints by which some forms of public gathering can appear politically intelligible while others cannot? I investigate this question by conceptualizing what I call the force of assembly. I argue that there is no essential form of political assembly. Instead, a politically intelligible assembly is a performative effect of gathering under and according to compulsory norms whose intersecting logics operate materially, collectively and affectively; these are the logics by which public meanings about assembly are created. An assembly’s political intelligibility rests on its perceived compliance with these compulsory norms. Materially, people on the streets may make political claims, but the conditions of their embodied presence in public space shape the gathering’s political intelligibility, embodying public meanings that exceed discursive articulation. Collectively, a gathering associated with a collective identity appears to be the work of an intelligible political actor. Affectively, the moods, emotions and feelings connected with an assembly can enable or obscure its political intelligibility. However, materially, collectively and affectively generated meanings do not result solely from the actions of those gathered on the streets. An assembly’s performative force also depends integrally upon public audiences attending to and interpreting it. I advance this theoretical argument by analyzing two instances of public gathering in contemporary Los Angeles history, one for many audiences politically intelligible and the other not: the 1994 anti-Proposition 187 march to City Hall and the 1992 Uprising / Riots. This study seeks to contribute to radical democratic theories of collective political action, offering a more complex and empirically grounded account of the multidimensional channels by which moments of collective political action can carry normative force as political assemblies. My hope is that examining the conditions of possibility for intelligible popular action can illuminate the contingencies of our social meanings and practices and contribute to a world where different forms of worldmaking can flourish.