The limited research available on writing in Grade 1 led to the development and implementation of an intervention for students who were performing below expectations. Ten students participated in a writing intervention for 11-13 weeks. A multiple baseline design across three units of instruction was focused on (a) paragraph structure, (b) sentence structure and handwriting, and (c) vocabulary and spelling allowed for analysis of the effects of the intervention. Treatment effects were evident from visual analysis, nonoverlap statistics, and multilevel modeling. Descriptive data collected on literacy measures administered before and after the intervention also indicated growth. Educator ratings of student writing and social validity surveys provide further evidence that improvements in student writing were apparent. Students also provided favorable input. These results indicate the malleability of writing behavior in at-risk first-grade students. Although preliminary findings are promising, iterative development would help improve this intervention and determine its efficacy with a broader sample of students. [This is the online version of an article published in "Journal of Educational Research." For the final published version of this article, see?EJ1303098.]