This study investigates vocabulary development over one year for three young children with specific language impairment (SLI). Rate of vocabulary development and use of nouns and verbs relative to total vocabulary is compared with a larger sample of younger, typically developing children. Communicative Development Inventory (CDI) data were collected and results provided a typically developing trajectory against which the children with SLI could be compared. The two groups show similar growth curves at these early stages. Findings are discussed with reference to previous work on vocabulary development and methodological differences between parental report and naturalistic data collection.