Hurricane Katrina has mobilized community-based environmental justice organizing and advocacy and injected a strong social justice analysis of extreme weather events and disaster recovery. Using interviews and observations with New Orleans activists and organizations, we examine three community and advocacy-based rebuilding and organizing projects that arose as a result of diminished local and federal government infrastructure and regulatory engagement: 1) a labor-environment coalition which rebuilt a single neighborhood block as a demonstration project that also provided safety and health training; 2) activists' analyses of sludge toxicity in diverse neighborhood and point source locations; and 3) community organizing to address the re-opening of public schools on contaminated land. This leads us to a broader examination of neighborhood activism regarding rebuilding, barriers and opportunities posed by political and state entities, and the connection between environmental hazards and public health infrastructure problems. An in-depth look at these three case studies underscores the importance of community-based environmental justice organizations for building grassroots infrastructure for effective disaster planning and to ensure that a foundation exists to advance recovery efforts, particularly in situations when government infrastructure and support is lacking. © 2011, Mary Ann Liebert, Inc.