The Community Outreach and Health Disparities Laboratory at Memorial Sloan-Kettering Cancer Center is a rapidly evolving program of research and program development dedicated to improving access to care, quality of care and quality of life among medically-underserved communities. Our work involves action research with community organizations and health delivery systems to address health disparities in cancer and HIV/AIDS. As part of this work, we are developing new quantitative and qualitative methods appropriate for understanding processes of change in diverse settings and communities.