We present a neutron-scattering study of depletion interactions in a mixture of a hard-sphere-like colloid anda nonadsorbing polymer. By matching the scattering length density of the solvent with that of the polymer, wemeasured the partial structure factor Sc(Q) for the colloidal particles. It is found that the measured Sc(Q) fordifferent colloid and polymer concentrations can be well described by an effective interaction potential U(r)for the polymer-induced depletion attraction between the colloidal particles. The magnitude of the attraction isfound to increase linearly with the polymer concentration, but it levels off at higher polymer concentrations.This reduction in the depletion attraction presumably arises from the polymer-polymer interactions. The experimentdemonstrates the effectiveness of using a nonadsorbing polymer to control the magnitude as well asthe range of the interaction between the colloidal particles. @S1063-651X~96!10911-9#