Nouns and verbs differ in their neural and psycholinguistic attributes. It is not known whether these differences lead to distinct patterns of response to treatment for individuals with word retrieval impairments associated with aphasia. Eight participants with naming disorders induced by left hemisphere strokes were treated with a semantic-phonologic treatment protocol for nouns and verbs using a single participant multiple baseline design. We measured treatment gains in a picture naming measure and other secondary language and communication measures. Treatment led to improved picture naming for trained nouns and verbs in five of eight patients, with no difference evident between nouns and verbs. Improvements for untrained words were minimal. Improvement in verb retrieval was associated with increases on a functional measure of communicative effectiveness. Improvement for nouns and verbs was associated with severity of word retrieval impairment at onset. Although distinct in neural and psycholinguistic attributes, nouns and verbs were affected by treatment in a similar pattern in this group of individuals. Training-specific effects suggest the need for careful selection of training words to have potential for functional benefit in daily communication. © 2007 Psychology Press.