Jens Bolte and Rainer Glaser Quantum ergodicity for Pauli Hamiltonians with spin 1/2 (62K, LaTeX2e) ABSTRACT. Quantum ergodicity, which expresses the semiclassical convergence of almost all expectation values of observables in eigenstates of the quantum Hamiltonian to the corresponding classical microcanonical average, is proven for non-relativistic quantum particles with spin 1/2. It is shown that quantum ergodicity holds, if a suitable combination of the classical translational dynamics and the spin dynamics along the trajectories of the translational motion is ergodic.