We propose and demonstrate a process for fabricating large-area photonic-crystal slabs with designed defects. The process takes advantage of a property we have observed in certain photoresists. These resists, which under ultraviolet illumination exhibit positive tone, behave as negative resists under electron-beam exposure. Electron-beam exposure is used first to expose defect structures, which renders them insensitive to further exposure. Subsequently, a large area is exposed with a photonic-crystal structure consisting of a regular pattern of holes defined by the interference between several ultraviolet laser beams. Upon chemical developing, a large photonic-crystal region with local patterned defects is created in the resist. The patterned resist is used as an etch mask for etching a slab of high-refractive-index material. In this article, we describe the fabrication process and present fabricated structures. (C) 2004 American Vacuum Society.