A committee of the National Research Council (NRC) will conduct a two-part study to assess and advance current approaches to toxicity testing and assessment to meet regulatory data needs. In the first part of the study, the committee will prepare a report reviewing selected aspects of several relevant reports by EPA and others on this topic. In the second part of the study, the committee will prepare a second report presenting a long-range vision and strategic plan for advancing the practices of toxicity testing and human health assessment for environmental contaminants.