Self-regulation emerges throughout early childhood, and predicts later success in socially and cognitively challenging situations. Vygotsky proposed that symbols, particularly words, serve as mental tools to be used in service of self-regulation. Cross-sectional research indicates a positive but inconsistent association between language and self-regulation skills throughout toddlerhood, but research has not accounted for general cognitive development, nor gender differences in these domains. We used growth modeling of longitudinal data for 120 toddlers collected when children were 14, 24, and 36 months to test the impact of two expressive language skills – spoken vocabulary and talkativeness – on the growth of toddlers’ self-regulation, and to determine whether associations between these domains exist when controlling for cognitive development. Results reveal gender differences in self-regulation trajectories, and in the impact of language on self-regulation. Vocabulary is a better predictor of self-regulation than talkativeness, and both concurrent and prior vocabulary positively predicted children’s levels of self-regulation. When cognitive development was controlled, 24-month vocabulary still predicted the trajectory of self-regulation. Results reveal that, even in early development, words are tools that can be applied to the task of self-regulation, and may be a more necessary tool for boys than for girls at this age.