The Physics Department and the Institute of Nuclear and Particle Physics support some of the leading research groups in this basic area of physics. Faculty members are the spokesmen for experiments that test fundamental aspects of nucleon and nuclear structure. These include experiments at the Stanford Linear Accelerator Center (SLAC) on the origin of the nucleon's spin, the details of the charge distribution of the neutron at Thomas Jefferson National Accelerator Facility (TJNAF), and a precision measurement of pion beta decay at the Paul Scherrer Institute (PSI). At SLAC the inelastic scattering of polarized electrons from polarized nucleon targets allows a detailed investigation of the spin structures of the nucleon. These measurements provide the best determination of how the quarks and gluons contribute to the fundamental spin of the nucleon. There is active research and development of high-power polarized targets, using high-field superconducting magnets, low-temperature refrigerators, and high-frequency microwaves. Electron paramagnetic resonance characterization of these targets is proceeding together with theoretical and computational modeling of local hyperfine interactions that contribute to dynamic nuclear polarization. At TJNAF an extensive series of experiments has been approved, including a measurement of the electric charge form factor of the neutron. The experimental measurements are complemented by strong theoretical support in the Department. This theoretical effort involves work in relativistic chiral quark models, spontaneous chiral symmetry breaking, quantum theories based on light-front formalism, and perturbative quantum chromodynamics (QCD) phenomenology, including studies of power corrections to the nucleon/nuclear structure functions, quark-hadron duality and low Bjorken x physics.