Research Findings: Shared book reading provides a meaningful context for rich conversations to occur between a child and an adult and offers opportunities for children to be exposed to a range of vocabulary and concepts that often extend beyond their everyday experiences. Few studies have examined parent-child shared book reading as a context for embedding mathematical discussion. The purpose of this study was to examine systematically the effect of training parents to focus on mathematical concepts and vocabulary during shared book reading. Specific research questions were as follows: (a) Did parents increase their use of math talk during shared storybook reading following training? (b) Did parents generalize intervention strategies? And (c) did children increase their use of math talk during shared storybook reading? Results from a yoked multiple-baseline design with 6 dyads indicated variability across the dyads with 2 general patterns. Math talk increased following training for 3 of the dyads, whereas verbal mathematical behavior did not show consistent change for the other 3 dyads. Practice or Policy: Results are discussed in the context of home support for early mathematical development.