Studies on graded readers used in extensive reading have tended to focus on vocabulary. This study set out to investigate the linguistic profile of graded readers, taking into account both grammar and lexis. A corpus of 90 readers were tagged according to the variables in Biber's Multidimensional (MD) analysis, using the Multidimensional Analysis Tagger (MAT). These variables were analysed using latent class cluster analysis to determine whether the graded readers can be grouped by similarity in linguistic features. While MAT analysis surfaced more similarities than differences within the corpus, latent class clustering produced an optimal 3-class model. Post-hoc concordance analyses showed that graded readers may be categorised as having three classes of complexity: beginner, transitional, and advanced. The findings in the study suggest that selection of reading materials for extensive reading should take into consideration grammatical complexity as well as lexis. The linguistic profiles compiled in this study detail the grammatical structures and the associated lexical items within the structures that teachers may expect their students to encounter when reading graded readers. In addition, the profiles may be of benefit to teachers seeking to supplement extensive reading with form-focused instruction.