Research Findings: These two studies examined the different mathematical opportunities provided in preschool classrooms, with a particular focus on the availability of mathematical-themed books in classroom libraries. In study one, we interviewed teachers (N= 150) using an online survey to assess the content of preschool classroom libraries. In study two, we interviewed eight preschool teachers to examine their perceptions of how they teach mathematics and if they view the classroom library as a place for mathematical skill acquisition. Results of the online survey indicated that while teachers encourage the use of classroom libraries, these contained statistically fewer mathematics themed books. Teachers also spontaneously reported that mathematics was something done in the “math center” and not the library. Preschool teachers reported providing many mathematical opportunities throughout the day, but did not necessarily utilize the classroom library for mathematics. Policy or Practice: Given the prevalence of classroom libraries in preschools, we may be missing an important means of providing mathematical exploration, exposure, and opportunities for young children. This potential missed opportunity is an area for additional research. (author abstract)