We request funds to support a community workshop to guide US efforts in establishing a US Interferometric Synthetic Aperture Radar (InSAR) mission. InSAR is a new type of space-based radar observation that allows ground displacements from earthquakes and other sources to be measured over many millions of pixels (each representing a resolution of about 10-30 meters) to a displacement accuracy of several millimeters. InSAR images also have significant value in monitoring volcanic eruptions; in weather forecasting, inasmuch as the radar reflections are sensitive to soil moisture variations; in ice and glacier studies; and in a variety of surface change and environmental applications, including estimates of wind velocity and direction, and detection of oil slicks. The proposed workshop will take place October 20-22, 2004 in Oxnard, California. We anticipate receiving funds from NASA for workshop support. Funds will also be requested from the USGS. The Southern California Earthquake Center will provide administrative support for the workshop.