The symposium was held at the National Institute of Standards and Technology in Boulder, Colorado on Nov. 15, 1997 to celebrate the career of James E. Zimmerman. He was coinventor of the radio-frequency Superconducting QUantum Interference Device and coined the name "SQUID." A highly sensitive detector of magnetic fields, the SQUID is limited only by fundamental quantum uncertainties, and its potential was immediately recognized. Later, at the National Bureau of Standards (now NIST), Zimmerman pioneered many applications of the SQUID, from measurement science to geomagnetism and magnetoencephalography. As a tribute to his career, the symposium presented talks by prominent researchers reviewing the SQUID's origin and the present state of the art.