The relationship between working memory capacity and writing ability was examined via a linguistic analysis of student essays. Undergraduate students (n = 108) wrote timed, prompt-based essays and completed a battery of cognitive assessments. The surface- and discourse-level linguistic features of students' essays were then analyzed using natural language processing tools. The results indicated that WM capacity was related to surface-level, but not discourse-level features of student essays. Additionally, the results suggest that these relationships were attenuated for students with high inferencing skills, as opposed to those with lower inferencing skills. [This paper was published in the Proceedings of the 38th Annual Meeting of the Cognitive Science Society 2016, p2483-2488.]