AbstractAn examination of the molecular weight distribution via gel permeation chromatography of the Dow S‐109 and NBS 705 polystyrenes has revealed that these two samples are the same. Within experimental error, both polystyrenes possess identical number ‐and weight‐average molecular weights. In addition, the molecular characteristics of the Dow S‐102, Dow S‐105, Dow S‐108, and Dow S‐111 polystyrenes were determined. Of the samples examined, the near‐monodisperse NBS 705, Dow S‐102, Dow S‐109, and Dow S‐111 were found to have either low or high molecular weight components in their molecular weight distributions. The characterization results on the Dow S‐109 polystyrene fail, though, to explain the melt viscosity anomalies reported for this polymer.