A sociocultural view of learning proposes that learning involves becoming enculturated into a community of practice. A step along the way is learning to use the specialized language of such a community, as language is a crucial tool that regulates participation, mediates cognition and plays a central role in the development of thought. Problem-based learning (PBL), with its emphasis on collaborative discourse, provides opportunities for students to develop the conceptual language of a discipline, which in turn affects cognition. In a problem based undergraduate Educational Psychology course, many psychological theories, concepts and principles are introduced to pre-service teachers. During the course, as students learn through problem solving, they engage with new knowledge. This evolving knowledge requires new discourse structures that will allow students to express their new ideas and that will ultimately structure students' ways of knowing. The content of group and individual artifacts is analyzed to examine how PBL influences students' language and knowledge development over the course of the semester in an Educational Psychology class (n = 34). The goal of this paper is to present these analyses and to discuss how the change affects students' language and knowledge.