To communicate effectively with the public during an emergency, health officials need to find out in real time what Americans know and believe, whom they trust, and what actions they are taking in response to the crisis. Short-duration surveys can provide vital information to guide public officials in their response to events and their communication efforts. Prior research has shown that such surveys, when statistically re-weighted, can offer timely results without unacceptable risk of bias. Using examples from public opinion surveys during the anthrax attacks of 2001, this article examines the role such surveys can play during a public health crisis.