Deaf students often differ from their hearing peers in written language development. Providing developmentally appropriate instruction is ideal, yet current methods of writing assessment do not provide teachers with sufficient information regarding the written language (i.e., syntactic) development of deaf students. In this research, we use a Systemic Functional Grammar (SFG) approach to language analysis to provide teachers with a new way to evaluate deaf students' writing. This project consisted of two studies. The first study focused on determining whether SFG analysis could be helpful for teachers of the deaf. The second study focused on mapping a trajectory of the written language development of deaf students and the development of written language inventory for teachers of the deaf. This inventory, along with additional evaluation tools, has the potential to impact both objective setting and instruction. [This is the online version of an article published in "Psychology in the Schools."]