Many students with learning disabilities (LD) struggle to develop text-writing fluency: the skill of accurately and efficiently composing multiple words into sentences and passages understandable to readers. In prior studies, researchers have used instructional assessments to control for task difficulty and identify precise areas of text-writing fluency to address using explicit instruction. In this article, guidance is provided on how to use instructional assessments--a type of curriculum-based assessment--to inform explicit instruction of text-writing fluency for students with LD. In addition to detailed steps, considerations for implementation and variation are discussed.