What if we could start over and build the Internet from scratch? How could it be rebuilt or reimagined as more equitable and just? For more than eight years, Britt S. Paris investigated alternative Internet infrastructure projects, conducting interviews, site visits, and policy analysis. In this expansive and interdisciplinary study, Paris critically examines the myriad and contradictory promises, utility, and obstacles to building a completely new Internet. Radical Infrastructure locates and analyzes the boundaries of how people and groups imagine, build, deploy, maintain, and use the Internet as they survive—and even dare to thrive—in challenging political, economic, and environmental contexts. Ultimately, Paris encourages active reflection among scholars, policymakers, and activists and reveals more grounded imaginaries, tactics, and opportunities for future people-centered projects.