The treatment of collective variables within the BRST formalism is applied to the problem of the coupling between the particle and the rotational degrees of freedom. The usual Coriolis interaction emerges as the leading order term, but higher order couplings may be systematically obtained as well. Several significative differences with the particle‐rotor model are discussed. The Elliott SU(3) model is used as an example which includes almost all the complications to be expected in more realistic calculations.