Did the protests surrounding recent climate summits mark the emergence of a climate justice movement? We analyze responses to surveys of three large demonstrations in Copenhagen, Brussels, and London, organized in connection with the 2009 UN Climate Change Conference (COP-15) to determine who demonstrated, and how and why the collective action frames employed by demonstrators varied. The demonstrations were products of the mobilization of broad coalitions of groups, and we find significant variation in demonstrators’ prognostic framings—the ways in which they formulated solutions to climate problems. Most notably, there was a tension between system-critical framings and those oriented around individual action. A large proportion of demonstrators expressed affinity with the global justice movement (GJM), but we find little evidence of an emerging “climate justice” frame among rank-and-file protesters. Individual variations in framing reflect differences between the mobilization contexts of the three demonstrations, the perspectives and values of individual participants, and the extent of their identification with the GJM.