Plans for an intensive cirrus-cloud field experiment are described. The Cirrus Intensive Field Observations (Cirrus IFO) is a major component of the First ISCCP3 (International Satellite Cloud Climatology Project) Regional Experiment (FIRE). The field campaign was conducted in Wisconsin during October 1986. Observing systems include satellites, “cloud” lidars, a very high-altitude, satellite-simulator aircraft platform, two research aircraft instrumented for detailed in situ microphysical and radiometric observations, a Doppler lidar, numerous passive surface-radiation sites, and a rawinsonde network. This is the first cirrus experiment involving such a comprehensive observing system.