A criterion is developed for the selection of the best pairing of the control and manipulated variables of a multiloop control system. This criterion is based on the difficulty caused by the interaction terms (the off-diagonal elements) in finding the inverse of the steady state gain matrix. From an analysis based on the proposition that the most desired or best pairing is that one for which the system most closely resembles a set of independent single-loop systems, a quantitative measure of the best pairing is obtained. Although the development of the pairing criterion is based on purely algebraic principles, the validity of the pairing criterion is evident from analogous developments obtained within the control framework. Furthermore, it is shown that the pairing criterion may be used to determine the stability of a multiloop control system, thus enhancing the value of the criterion presented.