The complexity of many urban health problems often makes them ill suited to traditional research approaches and interventions. The resultant frustration, together with community calls for genuine partnership in the research process, has highlighted the importance of an alternative paradigm. Community-based participatory research (CBPR) is presented as a promising collaborative approach that combines systematic inquiry, participation, and action to address urban health problems. Following a brief review of its basic tenets and historical roots, key ways in which CBPR adds value to urban health research are introduced and illustrated. Case study examples from diverse international settings are used to illustrate some of the difficult ethical challenges that may arise in the course of CBPR partnership approaches. The concepts of partnership synergy and cultural humility, together with protocols such as Green et al.'s guidelines for appraising CBPR projects, are highlighted as useful tools for urban health researchers seeking to apply this collaborative approach and to deal effectively with the difficult ethical challenges it can present.