Grammatical complexity constitutes an indispensable subconstruct of L2 writing ability. Nonetheless, rating scale descriptors for grammatical complexity have heavily relied on degree modifiers or adjectives. Thus, this study attempts to explore the potential for the use of nominal modifiers as discriminators for adjacent levels of L2 writers in the context of an English Placement Test. This study analyzed 374 argumentative essays written by international undergraduates. Seven nominal modifiers in the developmental stages of grammatical complexity were examined and a cumulative ordinal logistic regression model with proportional odds was fitted to explore the relative effects of those grammar features on placement decisions. Four nominal modifiers were found to be positively associated with placement decisions, after adjusting for the effects of other variables. One educational implication is for the use of nominal modifiers to be incorporated into rating scale descriptors as discriminators for L2 writers who are not advanced enough to be exempted from an English Placement Test.