This study explores the effects of training parents to administer focused stimulation intervention to teach specific target words to their toddlers with expressive vocabulary delays. Twenty-five mothers and their late-talking toddlers were randomly assigned to treatment and delayed-treatment (control) groups. Vocabulary targets were individually selected for each toddler based on the child's phonetic repertoire and parent report of vocabulary development. Following treatment, mothers' language input was slower, less complex, and more focused than mothers in the control group. Concomitantly, their children used more target words in naturalistic probes, used more words in free-play interaction, and were reported to have larger vocabularies overall as measured by parent report. In addition, the treatment had an effect on language development -- children in the experimental group used more multiword combinations and early morphemes than children in the control group. The implications of these results are discussed with regard to the role of focused stimulation intervention for children with expressive vocabulary delays.