Latino day laborers often work at dangerous construction sites with little power to change conditions. We describe the development, implementation, and early-stage results of a program to train immigrant day laborers as safety liaisons. These are construction workers prepared to recognize and respond to health and safety hazards. Based in Newark, NJ, the project involves collaboration between New Labor, a membership-based worker center, and university researchers and labor educators. Safety liaisons undergo training and receive ongoing support for their roles. Both qualitative and quantitative data are collected to monitor progress. Although lacking in formal authority, safety liaisons have prompted improvements at specific sites, filed OSHA complaints, and developed a local worker council. Participatory training methods, opportunities for leadership outside the classroom, and participation in project planning have strengthened liaisons' effectiveness, leadership skills, and commitment. The safety liaison approach could be adapted by worker centers and their partner organizations.