This Resource Letter provides a guide to literature on the standard model of elementary particles and possible extensions. In the successful theory of quarks and leptons and their interactions, important questions remain, such as the mechanism of electroweak symmetry breaking, the origin of quark and lepton masses, the source of the baryon asymmetry of the Universe, and the makeup of its matter and energy density. References are cited for quarks and leptons, gauge theories, color and chromodynamics, weak interactions, electroweak unification, CP violation, dynamics of heavy quarks, Higgs bosons, precision electroweak measurements, supersymmetry, dynamical electroweak symmetry breaking, composite quarks and leptons, grand unification and extended gauge groups, string theories, large extra dimensions, neutrino masses, cosmic microwave background radiation, dark matter, dark energy, accelerator facilities, and non-accelerator experiments.