The apolitical legitimacy of "evidence-based medicine" offers a practical means for ethnography and critical social-science-and-humanities-of-health theory to transfer survival resources to structurally vulnerable populations and to engage policy and services audiences with urgent political problems imposed on the urban poor in the United States that harm health: most notably, homelessness, hyperincarceration, social service cut-backs and the War on Drugs. We present four examples of collaborations between ethnography and clinical research projects that demonstrate the potentials and limits of promoting institutional reform, political debate and action through distinct strategies of cross-methodological dialog with epidemiological and clinical services research (Authors).