  We give a formulation of quantum ergodicity for Pauli Hamiltonians with
arbitrary spin in terms of a Wigner-Weyl calculus. The corresponding classical
phase space is the direct product of the phase space of the translational
degrees of freedom and the two-sphere. On this product space we introduce a
combination of the translational motion and classical spin precession. We prove
quantum ergodicity under the condition that this product flow is ergodic.
