Vital nuclear physics experiments using leptonic probes have also been carried out at three laboratories whose main mission is in high energy physics: CERN; Fermilab; and SLAC. A major new effort is now underway at DESY. The extremely high energies of these facilities has supported measurements providing insight into the spin structure of the nucleon and a variety of other measurements uniquely sensitive to the underlying quark structure of nuclei. The NSAC Long Range Plan must make provision for the continuation of this type of measurement as high-return initiatives surface in the future.