This study explores the identity formation of two postsecondary language teachers and course coordinators--one in German and one in French--as they created intermediate-level, content-based social justice curricular units for a multiyear project. Using a multiple-case-study methodology and cultural--historical activity theory, this qualitative investigation answers the following research question: How do experienced postsecondary language teachers (re)construct and (re)negotiate their identities while developing social justice teaching materials? Findings, based on multicycle descriptive coding, reveal that participants' past experiences, personal values, feelings of self-doubt, and positionality as content-based language teachers influenced their language teacher identity, as did tensions within and across three activity systems: the curriculum development project, classroom teaching, and the coordination of multisection courses. These findings have important implications for teacher professional development and community building related to social justice in language education.