Abstract: Described are thermoplastic or thermoset polymer and resin compositions (e.g., nylon, polyvinylchloride, phenolics, etc.) containing a bis-sulfonamide or polyhaloaromatic monosulfonamide in quantity sufficient to plasticize the resins and polymers. The polyhaloaromatic monosulfonamide contains (a) from 7 to 30 carbon atoms, (b) from 2 to 12 chlorine and/or bromine atoms, (c) one nitrogen atom, (d) an aromatic group, bonded to the sulfur atom, in which at least two chlorine or at least two bromine atoms or at least one chlorine atom and at least one bromine atom are directly bonded to the aromatic ring system, and (e) one or two aliphatic, cycloaliphatic, or aromatic organic groups bonded to the nitrogen atom, one such organic group, when an aromatic group, optionally being substituted by one or more bromine and/or chlorine atoms. The bis-sulfonamide contains at least two aromatic rings and from 14 to 30 carbon atoms in the molecule.