Social movement scholars have argued that social movement mobilization at the micro level is a sequential multi-stage process but have ignored the first stage of this process, the creation of a pool of supporters from which movements can potentially draw participants, when analyzing the Eastern European protest wave of 1989. I question the assumption that such a pool of potential participants was ready-made and ask how it was formed. To address these concerns, I analyze the mobilization context in which the successful protest wave of 1989 developed. I contrast it with the mobilization contexts of the unsuccessful Chinese and Albanian cases. My concrete research question is: What were the societal institutional environment and the political culture in Eastern Europe in the late 1980s within which protest movements could gather mass support and within which democracy could take root? I argue that the Eastern European democratic impetus was grounded within a cosmopolitan world culture. I also argue that Eastern European transnational social movements were major cosmopolitan actors in creating and promoting this culture over more than a decade. Thus, cosmopolitanism served as a mobilization potential while the development of cosmopolitanism appears to have been the first stage of the protest mobilization process and subsequent democratization in Eastern Europe in the late 1980s. My evidence comes from various sources, including a dataset on transnational social movement organizations around the world from 1953 to 2003, the World Value Survey, data on movement membership and reach, and semi-structured interviews with members of the most prominent movement in the region, the Esperanto movement, in four Eastern European countries