This study investigated the use of cognitive state verbs (CSVs) and complement clauses in children with specific language impairment (SLI) and their typically developing (TD) peers. In Study 1, conversational samples from 23 children with SLI (M = 6;2), 24 age-matched TD children (M = 6;2) and 21 vocabulary-matched TD children (M = 4;9) were analysed for the proportional use of CSVs, verb types, co-occurrence with complement clauses and syntactic frame types. Children in all three groups had similar performance in all measures. Study 2 compared a subset of children on CSV use in conversational and narrative/expository samples. Conversation elicited more high-frequency verbs, whereas narrative/expository samples elicited more low-frequency verbs. Children with SLI used fewer different verbs and were less likely to combine low-frequency verbs with a complement clause than their TD peers. We conclude that these observed deficits can be attributed to limitations in lexical knowledge rather than a syntactic deficit. (Contains 5 tables.)