The purpose of the study was to better understand the phenomenon of exploring early mathematics through book reading. The study centers on Head Start and lays on Bronfenbrenner’s bioecological framework). Two sub-questions guided the qualitative single case study of six Head Start adult participants (teachers, parents, administrators): (1) What are Head Start participants’ experiences in exploring early mathematics through picturebooks? and (2) What do Head Start participants say about exploring early mathematics through picturebooks? Findings showed that participants expressed interest toward exploring early mathematics through picturebooks. Picturebooks were commonly used in the classroom but also accessible for families. Participants provided evidence of mathematics practices and discussions around mathematics in the school and in the home. The participants’ sayings and experiences in exploring early mathematics through picturebooks aligned with child development and contexts of learning, two cornerstones of Developmentally Appropriate Practice (DAP), but potential obstacles emerged. Implications for researchers and practitioners are discussed. (author abstract)