Writing is a critical academic and life skill, but many school-age children struggle with the complexity of written expression. Given the importance of writing, there is a clear need for a systematic approach to identifying and supporting struggling writers, including writers with learning and emotional disabilities. One such approach is known as Data-Based Instruction (DBI). In this manuscript, we present an overview of DBI and guidance on how educators can use the DBI steps with assessment data to inform their classroom writing instruction. Additional resources are shared to support teachers in using DBI with their struggling writers and writers with learning and emotional disabilities. [This paper was published in "Intervention in School and Clinic" v57 n3 p147-155 2022 (EJ1321339).]