The classical model for rotational magnetic moments in molecules is useful for elucidating physical description, although it must give way to quantum mechanics for fundamental formulation. A powerful method of approach, first applied to the problem by Wick, is afforded by the generalized theorem of Larmor, which is here derived from the equations of motion for a rotating molecule placed in a magnetic field. It is shown that the electronic motion relative to the nuclear frame must be perturbed by the Coriolis torque as a consequence of molecular rotation. The rotational magnetic moment of the molecular electrons can be considered to consist of two parts, one due to “rigid” motion together with the nuclear frame and the other to “nonrigid” motion, which is equivalent to that created by a magnetic field in a nonrotating molecule according to the relationH = −ω/γ.