Purpose: The aim of this study was to examine whether a verb-focused language intervention was effective in increasing children’s verb-vocabulary. In particular, this study investigated whether the treatment resulted in changes to children’s production of target words compared to control words for children who are late talkers. Method: The study utilised a single-subject, multiple baseline across behaviours design. Four children, aged 26-to-39 months who exhibited delayed expressive language development participated in the study. At the beginning of the study, all children had poor expressive language performance indicated by a mean length of utterance two standard deviations below the mean expected for their age and limited vocabulary measured by the New Zealand Communicative Development Inventory: Words and Sentences. New verb-vocabulary items were randomly assigned to intervention and untreated control conditions and probed at regular intervals over a period of eight weeks. Results: All the participants showed increased use of the target verbs compared to the control verbs during the intervention and post-intervention phase. Conclusion: The findings suggest that a verb-focused language intervention was effective in increasing the verb-vocabulary of late talkers. Further research is warranted to determine whether similar results can be found with a larger cohort and whether these gains are sustained over time.