One of the principle concerns in the design of deep-ultraviolet (DUV) photoresist systems is optimization of the optical absorbance of the resist at 248 nm. Conventional novolak resists absorb strongly (OD greater than 1/micrometer), and are therefore not useful in the DUV. Most DUV formulations consist of a poly(hydroxystyrene)-based resin, a photoacid generator (PAG), and perhaps an additional component (crosslinker, dissolution inhibitor, dye, contamination stabilizer). There are multiple available PAGs, such as aryl onium salts, which have been designed to undergo efficient direct photolysis upon irradiation at 248 nm. Certain PAGs, however, are nearly completely transparent at this wavelength, yet are seen to function well in acid-catalyzed DUV resist systems. This is attributed to photosensitization of the PAG by the resin. Steady-state and dynamic fluorescence quenching and acid generation measurements were used to study this phenomenon and data for several systems are presented. It is concluded that both electronic energy migration and photoinduced electron transfer can play important roles in acid generation and that where possible, these functions should be incorporated into the design of high photospeed resist systems. Additional data is presented for a positive-tone photoresist with a photosensitizing dye component.