Detailed far-infrared dilution measurements on DMF in carbon tetrachloride provide data on which to base an assessment of the way in which both the short-ranged and long-ranged dynamics are dependent on the surrounding molecular interactions. While there is an obvious increase in the rate of the long-time reorientational motion on dilution, the short-time dynamics appear to be relatively weakly affected. This is considered to be due to competing effects of removal of solute-solute interactions and the addition of solute-solvent interactions. The data are interpreted with the aid of the Gaussian-‘cage’ model of Lynden-Bell and Steele, which reflects the large intermolecular mean-squared torques and the collective intermolecular dynamic origins of the high-frequency spectral density in the region of 80–120 cm-1.