Because few studies of disciplinary business writing have examined whether language features play a role in instructor assessment of student writing, this study explored the relationship between student language use and instructor essay scores. Undergraduate business students wrote a case study critique as part of their final exam, and their critiques were evaluated by their instructors for theory integration and essay structure. Student language use was analyzed in terms of error rate, lexical sophistication, lexical diversity, and phrasal complexity. Whereas lexical sophistication positively predicted instructor scores, error rate was a negative predictor of their assessment of business student writing.