An increased emphasis on writing standards has led many U.S. states to incorporate on-demand writing assessments into their test-based accountability system. We argue this creates political and pedagogical tensions for teachers to navigate. We discuss how rubric conceptualization (1) is a process wherein a teacher iteratively (co-)constructs meaning from a rubric's design via classroom instruction; (2) is informed by implicit theories of learning; and (3) often requires a teacher to negotiate the competing pedagogical and political meanings of a rubric. While test-based accountability frameworks promote rubric use that equates learning with student achievement, rubric conceptualization is a process where teachers have some agency to resist behaviorist approaches to instruction.