A brief review of necessary fundamentals relative to composite materials and viscoelasticity is provided. Subsequently the accelerated characterization techniques of Time Temperature Superposition and Time Temperature Stress Superposition are treated in detail. An experimental procedure for applying the latter to composites is given along with results obtained on a particular T300/934 graphite/epoxy. The accelerated characterization predictions are found in good agreement with actual long term tests. A postcuring phenomenon is discussed that necessitates thermal conditioning of the specimen prior to testing. A closely related phenomenon of physical aging is described. The effect of each on the glass transition temperature and strength is discussed. Creep rupture results are provided for a variety of geometries and temperatures for T300/934 graphite/epoxy. The results are found to compare reasonably with a modified kinetic rate theory. / Ph. D.