The purpose of this study was to test the effects of a comprehensive writing program for students with and without learning disabilities (LD) in inclusive general education classrooms. The program incorporated research-based components including instruction in a prewriting planning strategy, narrative text structure, writing strategies, and the process approach to writing. The study was conducted in five fifth-grade inclusive classrooms with 113 students (including 14 students with LD). A quasi-experimental comparison-group design was utilized, whereby three intact experimental classes received the writing intervention, and two intact comparison classes received traditional writing instruction. Measures included several writing indicators as well as state writing competency test scores. Results indicated that the students with and without LD in the experimental group made significant gains from pretest to posttest on several writing measures. Although students in the comparison group made some gains, the gains were related to fewer measures than the measures associated with experimental-group gains, and the effect sizes were smaller.