A conceptual model for vulnerable populations research relates resource availability and relative risk to health status. The model has a population-based focus that places responsibility for the collective health status of its citizens with the community. Vulnerable populations are social groups who experience limited resources and consequent high relative risk for morbidity and premature mortality. There is considerable research evidence to support the major relationships in the model. Conceptual links that need additional research are identified.Conclusions:
The implications for research include a variety of methodological problems related to recruiting and retaining participants, instrumentation, and data collection. Research designs are needed that move beyond descriptive and epidemiological approaches to interventional and outcome studies. Ethical consideration take on special significance with vulnerable populations.