During the 2011-2012 academic year, Texas public schools began administering the State of Texas Assessments of Academic Readiness (STAAR) in grades 3-8, replacing the old testing system, the Texas Assessment of Knowledge and Skills (TAKS). The TAKS-STAAR transition is a unique contextual backdrop for studying the role of state-mandated reading and writing tests in the assessment and learning environments of elementary and middle schools. In this study, drawing on extensive interview data, we detail the test-centric instructional practices related to reading and writing that were made evident during the transition and the uncertainties about instruction that were brought about by the implementation of the new test. We also propose three concepts that help explain how test-centric practices maintain their deep entrenchment in literacy instruction: transfer avoidance, managerial partitioning, and the acceptability of overreaching inferences. Although the transition described in this article is specific to one region of the United States, the findings have implications for future research in other settings.