Three experiments examined the involvement of orthography in spoken word processing using a task--unimodal auditory priming with offset overlap--taken to reflect activation of prelexical representations. Two types of prime-target relationship were compared; both involved phonological overlap, but only one had a strong orthographic overlap (e.g., "dream-gleam" vs. "scheme-gleam"). In Experiment 1, which used lexical decision, phonological overlap facilitated target responses in comparison with an unrelated condition (e.g., "stove-gleam"). More importantly, facilitation was modulated by degree of orthographic overlap. Experiment 2 employed the same design as Experiment 1, but with a modified procedure aimed at eliciting swifter responses. Again, the phonological priming effect was sensitive to the degree of orthographic overlap between prime and target. Finally, to test whether this orthographic boost was caused by congruency between response type and valence of the prime-target overlap, Experiment 3 used a pseudoword detection task, in which participants responded "yes" to novel words and "no" to known words. Once again phonological priming was observed, with a significant boost in the orthographic overlap condition. These results indicate a surprising level of orthographic involvement in speech perception, and provide clear evidence for mandatory orthographic activation during spoken word recognition.