Within single-mechanism connectionist models of inflectional morphology, generating the past-tense form of a verb depends upon the interaction of semantic and phonological representations, with semantic information being particularly important for irregular or exception verbs. We assessed this hypothesis in two experiments requiring normal speakers to produce the past tense from a verb stem that takes a regular or exceptional past tense. Experiment 1 revealed significant latency advantages for high- over low-imageability words for both regular verbs (e.g., "lunged" faster than "loved") and exception items (e.g., "drank" faster than "dealt"); but critically, this effect was significantly larger for exceptions than for regulars. Experiment 2 employed a semantic priming paradigm where participants inflected verb stems (e.g., sit) preceded by related (e.g., chair) or unrelated primes (e.g., jug) and revealed a priming effect in accuracy that was confined to the exception items. Our results are consistent with predictions from single-mechanism connectionist models of inflectional morphology and converge with findings from neurological patients and studies of reading aloud. © 2012 Copyright The Experimental Psychology Society.