The prevalence of late language emergence (LLE) in young children is high, comprising 10 to 20% of toddlers. Late language emergence refers to children who do not use at least 50 single words and 2-word phrases at the age of two. Current best practices for the under-three population with or at risk of having disabilities include the use of family-centered services in early intervention. One method of EI for LLE is caregiver-implemented interventions, where the caregiver learns techniques or strategies to help support their child's expressive language development. This service delivery model prioritizes building the family's capacity to support their child's development in natural environments and during natural routines. This study investigated the effectiveness of training caregivers to deliver an expressive language intervention with their late-talking toddlers. The intervention, Vocabulary Acquisition and Usage in Late Talkers (VAULT), uses principles of statistical learning to promote expressive language. Using low-pressure interactions, the intervention agent models target words at a very high frequency in varied contexts. The purposes of this study were to examine (a) how teaching and feedback affect caregivers' use of VAULT components with their late talking toddlers, (b) whether there is a subsequent change in the toddler's use of target vocabulary words, and (c) whether the intervention is valuable to the caregivers. The study used a multiple-probe multiple baseline across participants design with three caregiver-child dyads. Caregivers were trained online through video-conferencing to use the six components of VAULT with their late-talking children, then recorded themselves playing with their children while practicing the components of VAULT twice per week. The caregiver's use of the VAULT components were measured and reported to the family in weekly performance-based feedback provided via electronic communication. Visual analysis consistent with single-case research methodology was used to determine the effectiveness of the training and performance-based feedback on the caregivers' use of the VAULT components and changes in the children's expressive vocabulary. In addition, semi-structured interviews were conducted to investigate caregiver perceptions of the VAULT intervention. The findings revealed caregiver success in implementing VAULT's focused stimulation component and improvements over baseline in using the other five VAULT components. One child produced a target word during a maintenance session, and all caregivers reported changes in their children's prelinguistic skills. Additionally, all three caregivers found the intervention to be meaningful. This study highlights the feasibility of training caregivers to implement this expressive vocabulary intervention with their late-talking toddler. This study also includes implications for future practice and suggestions for future research. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]