The preceding chapters have discussed a wide array of biomarkers that can and are being used to demonstrate exposure to and effects of environmental contaminants. From this review, there can be little doubt that measurement of biomarker responses in organisms from contaminated sites offers great promise for providing information that can contribute to monitoring programs designed for surveillance, hazard assessment, regulatory compliance or for documenting remediation. The challenge is to develop and implement a research program that will permit this promise to be fully realized. Current understanding and application of biomarkers justifies their immediate implementation in an environmental monitoring program at a pilot-scale. However, the full potential of this methodology will be realized only after a larger data base of field and laboratory studies can be accumulated and analyzed. It is the purpose of this concluding chapter to present some thoughts on a research strategy that is needed to develop the data needed to validate biomarkers and provide the scientific understanding necesssary to interpret biomarker responses of environmental species. What is proposed is an evolving monitoring program that focuses broadly on evaluation of contamination in an array of ecosystem types. The challenges and obstacles to be addressed in such a program include the following: