The concept of children's theories is central to the approach of the municipal infant-toddler centers and preschools of Reggio Emilia, Italy. The author investigates children's theories about Judaism. Methods include semi-structured interviews and pedagogical documentation from American Jewish early childhood centers. Analysis involves open coding toward the development of a grounded theory positing that (1) children hold theories that impact the Jewish education they experience and (2) when the Jewish learning experience aligns with these inherent theories, children develop a new mental model, that they can make their mark on Judaism.