The extraordinary popular uprisings across the Arab world early in 2011 call for a radical revision of the stagnant, donor-driven definition of civil society as “NGOs” and “CSOs:” formal, often professional organizations duly licensed by their governments and registered with the UN to participate in white-collar policy-oriented workshops or provide welfare benefits to underprivileged social groups hurt by cut-backs in state programs. This paper will critique that notion and offer instead a more dynamic conceptualization of civil society that incorporates concepts of civic activism, popular collective action, and public civic realms (inspired in part by Gramsci and Habermas but also by analyses of the American civil rights movement and rapid change in Central Europe around 1990). This conceptualization invites analysis of spontaneous, informal, and/ or contentious activities and of openings of public civic spaces in urban squares and at intersections where citizens stand guard, clean trash or direct traffic. The paper offers a theoretically grounded thesis and a political argument. The theoretical intervention, tested comparatively against new empirical evidence from Egypt and Yemen, is that civil society is a variable (not a constant). It changes shape and size: it mobilizes, retreats, and takes different forms according to the dynamics, constraints, and opportunities of surrounding political, legal, and socio-economic circumstances and spacial geographies. Some times and situations tolerate lobbies and round-table talks; others inspire marches and strikes. Hopefully this framework offers insights into the sudden, transformational mobilization of Egyptian civil society and facilitates understanding of contrasts and similarities between the two cases of simultaneous mass action. The political assertion is that anti-populist “democracy and civil society promotion” as practiced by American, European, and UN agencies in the past two decades has proven irrelevant to the popular aspirations and actual prospects for democratization in the Arab world.