An increased emphasis on writing standards has recently led many U.S. states to incorporate text-based writing assessments into their test-based accountability system. This creates political and pedagogical tensions that teachers must navigate in their classroom use of writing rubrics. While prior research has focused on rubric design and/or the implementation of a rubric to judge its (lack of) utility as a tool for measurement or pedagogy, we consider a complex mediating process we call rubric conceptualization. We claim that rubric conceptualization is: (1) the process where a teacher iteratively (co-)construct meaning from a rubric's design into classroom instruction; (2) informed by implicit theories of learning; and (3) how a teacher negotiates the competing pedagogical and political meanings of a rubric. As a result, the process of rubric conceptualization presents a useful place for teacher education and teacher inquiry programs to more fully examine. While accountability frameworks likely constrain which rubric designs and curriculum activities teachers can engage in, rubric conceptualization is a process where teachers have some agency. In this way, rubric conceptualization presents an opportunity for teachers, along with their colleagues, mentors, and students to explicitly engage in meaning making that seeks to better align teacher instruction and student learning with sociocultural theory. [For the corresponding grantee submission, see ED608555.]