Academic writing possesses many characteristics that distinguish it from other registers, such as heightened information density, elaborated reference, and an impersonal style (Biber et al., 1999; Biber & Gray, 2016). However, disciplines manifest these language features differently (Biber & Gray. 2013), posing additional challenges to students as they acquire the specialized language of their field. For these reasons, understanding how student writing varies by discipline is essential for both pedagogy and research in writing development.

One of the most important distinguishing features of academic writing is the frequent use of complex noun phrases, which consist of a head noun modified by one or more premodifiers or postmodifiers (Biber et al., 1999; Biber et al., 2009; Biber & Gray, 2013). Among these noun phrase complexity features, the use of nouns as nominal premodifiers is particularly challenging due to the informational density they enable, the variety of meaning relationships they can express, and their potential ambiguity (Halliday, 1989; Biber & Gray, 2011; Wisniewski, 1996). Understanding how this type of complexity is used by student writers is therefore important in helping students meet the disciplinary communicative norms and expectations which are key to their advancement. To help achieve this goal, this study presents an analysis of the Michigan Corpus of Upper-Level Student Papers (MICUSP) examining the use of nouns premodified by nouns across 16 disciplines and four groupings based on the Becher-Biglan typology for identifying disciplinary families.

Results show that advanced student writing exhibits discipline-based variation in use of nouns with nouns as premodifiers in frequency, number of premodifying nouns, and type. Overall, findings align with previous work on disciplinary variation in other varieties of academic writing, including research articles and textbooks (Biber & Gray, 2013; Gray, 2015; Jalilifar et al., 2017), and lower-level student writers (Musgrave & Parkinson, 2014), showing higher frequencies of nouns premodified by nouns in the hard sciences than in the soft disciplines. Results support work on development of complexity in student writing (Biber, Gray & Poonpon, 2011) and suggest that upper-level student writing may be useful as a more accessible model for less proficient writers as they advance.