The effects of hydrostatic pressure on conjugated polymers, in particular polyphenyls (see Figure), have been studied using photoluminescence, absorption, photo-induced absorption. and Raman spectroscopies. The effect of pressure on the singlet and triplet excitons and polarons allows an understanding of localized and delocalized electronic states. M. Chandrasekhar was placed third for this work in the Advanced Materials Innovation Competition at the ICSM 2000 (see Adv. Mater 2000, 12, 1563 for details).