How do we move from defensive tactics that respond to the latest stages of capitalist urbanization, to transformative, strategic revolts, attacking the root causes and putting into practice alternative forms of urban life? One proposal for such a revolutionary alternative to capital's organization of our lived environment has been the commons, wherein inhabitants communally control the multi-faceted conditions that make up their daily reproduction. As a district behind the train station in the post-socialist city of Vilnius Lithuania faces gentrification, an autonomous community center there has sought to use commoning to resist. Taken up in the former state-socialist Eastern Block, commoning practices are embraced as a method for criticising the vicious wave of enclosures that began after the fall of state-socialism while at the same time not relying on the heavily stigmatized politics of state-socialism. Emerging from a process of thinking together, The Commonist Horizon features five interventions by movement thinkers. Beginning in the post-Soviet city of Vilnius, the dialogical process stretches outward to two other formerly state-socialist countries, and then beyond. Speaking from their experiences in social movement formations, the authors take up the lived experience of building what might be called urban commons, offering insights on the conceptual and political potentials and limitations of this terminology and associated practices.