Momentum is growing to improve the haphazard way in which America's environmental priorities are determined. Influential members of Congress and federal officials, among others, are asking whether regulators actually devote their greatest attention to problems presenting the greatest ecological and health risks. Priority-setting that is more rational and dispassionate, the argument goes, would provide the way out of the "ready, fire, aim" syndrome that characterizes a crisis-of-the-month approach. Increasingly, the technique of comparative risk assessment is advanced as the key to more efficient and sensible planning. Despite its growing popularity, however, serious doubts exist about the adequacy of risk assessment for setting priorities.Worst Things First? The Debate over Risk-Based National Environmental Priorities explores the controversy over selecting an approach to set he nation's environmental priorities. Even though broad agreement exists that change is necessary, some critics feel the scientific data-collecting procedures of risk assessment constitute an intolerable delay for addressing more obvious and urgent problems; others fear its widespread use in regulatory agencies would move Congress from the center of the advocacy process, replacing public participation with expert elitism. Additional major concerns are uncertainty (do we know a "bigger" risk when we see it?), commensurability (how can we compare cancers and whales?), and "asking the wrong questions" (is ranking problems an intellectual exercise when solutions are what the country ready needs?)Resources for the Future convened a major conference in November 1992 to present a forum where EPA could describe its current and future plans for pursuing risk-based planning and hear suggestions for improving its methods, process, and implementation. Advocates of paradigms that give risk assessment little or no role were also able to present their best argument Worst Things First? contains the papers of that important three-day meeting.As the papers reveal, participants generally agreed that several different, legitimate ways exist to target the nation's resources for environmental protection. Conferees clashed over whether these different approaches are complementary or at odds. Broad acknowledgment emerged that, despite EPA's emphasis on one particular paradigm to date, the nation is not yet ready to agree on how to set environmental priorities, let alone on what the priorities themselves should be.