Background: Use of numerical and spatial language, also known as math talk, is critical to the development of foundational number and spatial skills in early childhood. However, caregivers and children of low socioeconomic status (SES) tend to use less math talk than their higher-SES peers. Objective: The current efficacy study tested the hypothesis that quantity of math talk among low-SES caregivers and children is increased via a caregiver education curriculum aimed at improving caregivers' language input to children. Methods: Caregiver-child dyads (n = 37; children aged 17 to 36 months) participated in either the language input or a control intervention. Math talk (operationalized as number and spatial word tokens) was coded from video recordings of each dyad engaging in free play at three time points: baseline, post-intervention, and follow-up. Results: The language input curriculum significantly increased caregivers' amount of spatial talk and children's amount of number and spatial talk for up to 4 months after the intervention. Conclusions A caregiver education intervention increased caregivers' use of math talk, which resulted in higher math talk usage by their children. Further verification is needed through an adequately powered longitudinal randomized controlled trial.