The elastic and anelastic properties (in the megacycle frequency range), viscosity, and electrical resistivity of vitreous selenium near its glass transition temperature were measured as a function of the quench (or melt) temperature between 540° and 720°K. The measurements reveal a correlation between the various properties and the internal molecular structure of the material at the quench temperature. Ultrasonic attenuation below the glass transition temperature of vitreous selenium cannot originate from simple mechanical losses due to viscous flow. A phonon‐phonon scattering mechanism is suggested.