This ethnographic case study of a constructivist classroom examined the contextual, academic, and socio-cultural factors that influence kindergarten students’ mathematical literacy development. This study was done during the crucial junction between informal and formal mathematics and during the junction between informal and formal discourse that occurs in a kindergarten classroom. It also examined how disciplinary knowledge in mathematics is presented through classroom discourse. Five lenses drawn from the research literature were used to examine the data: (a) socio-cultural perspectives, (b) constructivist learning theory, (c) kindergarten curriculum, (d) language and discourse development, (e) mathematical process and content. A final framework was developed from the data collected. It included an (a) active restructuring of the environment (socio-cultural perspectives and constructivist learning theory), (b) language and discourse development, and (c) mathematical processes and content. This framework also delineated the elements observed in the classroom that support the final framework categories. The choice of curriculum should support collaboration between children and adults as well as collaboration between children. The choice of curriculum should encourage the complex use of language and support the transition to formal mathematical discourse (one of the dominant academic discourses). Children’s initiation and choice within the curriculum were found to be other key elements in this constructivist classroom. A system of continuous assessment and subsequent differentiation of instruction were two other essential elements in this reform mathematics classroom. Each of these key elements was shown to be important to foster mathematical literacy for all children. The role of socio-cultural perspectives ranging from Dewey’s structuring of the environment through Freire’s problem-posing curriculum to Delpit and Gee’s work on dominant discourses was highlighted in this complex study of a constructivist reform mathematics classroom. Areas for further research were also delineated.