Purpose: The purpose of this study was to evaluate if higher quantity, diversity, and grammatical informativeness of verb phrases in parent follow-in utterances (i.e., utterances that mapped onto child attentional leads) were significantly related to later expressive verb vocabulary in children with autism spectrum disorder (ASD). Method: We examined these associations in a sample of 31 toddlers with ASD and their parents in a longitudinal correlational study. Key aspects of parents' verb input were measured in 2 video-recorded 15-min parent--child free-play sessions. Child expressive verb vocabulary was measured using parent report. Results: An aggregate variable composed of the quantity, diversity, and grammatical informativeness of parent verb input in follow-in utterances across the 2 parent--child sessions strongly and positively predicted later child expressive verb vocabulary, total R[superscript 2] = .25, even when early child expressive verb vocabulary was controlled, R[superscript 2] change = .17. Parent follow-in utterances without verbs were not significantly related to later child expressive verb vocabulary, R[superscript 2] = .001. Conclusions: These correlational findings are initial steps toward developing a knowledge base for how strong verb vocabulary skills might be facilitated in children with ASD.