The AppCivist research project studies how new social media can support democratic assembly and participatory citizenship. The initiative is further rooted in the principles of social activism in that it aims to provide citizens with software systems that help them articulate projects, deliberate directly among themselves, and mobilize action. AppCivist is a platform for democratic assembly and collaborative decision-making. It helps people tackle problems in their communities, discuss and decide on ideas for solutions, turn ideas into proposals, edit and vote on proposals, and follow their implementation. AppCivist can facilitate ideation and help participants make better arguments through versioning, visualization, and collaborative deliberation. It encourages both on and off-line collaboration, addressing problems of scale in processes of direct democracy for small and large communities. The AppCivist team is currently collaborating with the City of Vallejo to use AppCivist for the city’s 2016 participatory budgeting campaign, available at vallejopb.appcivist.org. Participatory budgeting (PB) is an allocation process used in many cities around the world through which they commit a percentage of their annual budget (often 5%) to implement citizen-proposed projects. In PB, residents brainstorm, develop, and select project proposals that local governments are then committed to fund and implement. AppCivist is the result of a joint research initiative between the Social Apps Lab at CITRIS, UC Berkeley (http://socialappslab.org/), led by Professor Holston, where the project began several years ago, and the MiMove Research Team (https://mimove.inria.fr/) at Inria, Paris. The project received the UC Berkeley Chancellor’s Award for Campus-Community Partnership in 2016-2017.