A theory of minimum plastic spin (i.e. minimum relative rate-of-rotation of gross crystalline material and underlying atomic lattice) is proposed for the finite deformation of crystals, consistent with loading conditions and constraints. Three families of multiple-slip configurations of f.c.c. crystals are comprehensively investigated: (i) pure plane strain compression with a  axis of free extension; (ii) (110) loading in channel die compression; and (iii) all multiple-slip orientations in uniaxial tension. It is established that, in each case, minimum plastic spin uniquely predicts the experimentally observed behaviour.