Early career K-grade 2 teachers in a yearlong project explored discourse and mathematical argumentation through monthly professional development (PD) sessions. The goal of the project was to develop an understanding of the types of K-grade 2 tasks that promote argumentation, the types of discourse and argumentation that K-grade 2 students engage in, and participation structures and routines that K-grade 2 teachers can include to support their students. On the basis of experiences from the project, the authors highlight effective strategies for using language frames and public records to incorporate mathematical argumentation in the primary grades.