The World Social Forum (WSF) was conceived as a platform for exchanging experiences and interlinking effective action. It has brought together people and social movements opposed to neoliberalism, imperialism and the domination of the world by capital. In this book, leading intellectual-activists from four continents take stock of the WSF-experience until the early 2020s and suggest new paths for collaboration between all who build other possible worlds. Since the first meeting in Porto Alegre, Brazil, in January 2001, at least hundreds of thousands of activists have contributed to WSF activities locally, regionally, and globally. In the early years of the WSF, high hopes were often associated with the pink wave in Latin America, the Arab Spring, and similar events elsewhere. Many foresaw the coming of a systemic crisis and some activist-intellectuals even predicted with some accuracy the outbreak of the financial crisis. But not many predicted the strengthening of authoritarian capitalism that followed. The focus of this edited volume is on the multiple practices of struggle, organization, and conceptual innovation expressed in the main WSF slogan since 2001: "Another world is possible." Most chapters in this book were originally published in the journal Globalizations.