Quarks and leptons beyond the third generation

The possibility of additional quarks and leptons beyond the three generations already established is discussed. The make-up of this Report is (1) Introduction: the motivations for believing that the present litany of elementary fermions is not complete; (2) quantum numbers: possible assignments for additional fermions; (3) masses and mixing angles: mass limits from precision electroweak data, vacuum stability and perturbative gauge unification; empirical constraints on mixing angles; (4) lifetimes and decay modes: their dependence on the mass spectrum and mixing angles of the additional quarks and leptons; the possibility of exceptionally long lifetimes; (5) dynamical symmetry breaking: the significance of the top quark and other heavy fermions for alternatives to the elementary Higgs Boson; (6) CP violation: extensions to more generations and how strong CP may be solved by additional quarks; (7) experimental searches: present status and future prospects; (8) conclusions.