The purpose of this study, secondary data analysis, was to analyze the argumentative and informative essay writing of middle school students with disabilities. Inflectional, derivational, and compound word morphological forms within 360 essays were coded and analyzed using descriptive and inferential statistics. Results are grouped into categories by grade, subject (science and social studies) and genre (argumentative and informative) of writing. Correlational analysis was used to examine the relationship between morphological form use and quality and quantity writing scores. Results indicate that students in middle school are able to use inflectional, compound, and derivational morphological forms in their content area writing. Implications for research and practice are included. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]