The purpose of this study was to explore the ways instructors' subject matter beliefs regarding mathematics shape their courses in a community college environment. Data were collected and analysed from instructors' philosophical definitions of mathematics and observations of teaching episodes using a constructivist grounded theory research design. Findings show instructor beliefs separate mathematics discourses into subcultures of workplace, applied and academic mathematics communities with a perceived need for future mathematics assigned to each partition. In partitioning mathematics courses, instructors need to become aware of the possible shifting of content which can be inclusive and exclusive of needed academic mathematics. The knowledge learned can be incommensurable between these disjoint subcultures and can become a barrier to the future mathematics learning needs of workers in a knowledge-based society. (Contains 2 tables and 2 figures.) Appended are: (1) Interview Protocol One; (2) Concept Map Directions; and (3) Interview Protocol Two. (Contains 2 figures and 2 tables.) [This paper was published in: K. Safford-Ramus (Ed.) "A Declaration of Numeracy: Empowering Adults Through Mathematics Education, Proceedings of the 15th International Conference of Adults Learning Mathematics, Philadelphia, PA" (pp. 85-101), London: Adults Learning Mathematics: An International Research Forum.]