The idea that reading model essays facilitates better writing is generally accepted in second language writing literature. As such, anthologies of model essays are often selected for inclusion in writing centre self-access library shelves. When selecting these texts, readability is often considered via the application of quantitative readability formulae (e.g. the Lexile Readability Formula). Unfortunately, such formulae only measure two (i.e. semantic, syntactic) of the many features that impact readability, leaving other features that require qualitative consideration (e.g. signal words, SWs) unexplored. To address this, this article reports the findings of a sequential, mixed-methods study conducted in a Taiwanese university writing centre context that explored how SWs affect post-secondary English language learners' perceptions of ease and difficulty when reading model essays excerpted from anthologies. The inferential statistics showed that the informants (students who visited the writing centre) ranked the essays' ease and difficulty significantly differently than the Lexile Formula. The qualitative exploration found that SWs (e.g. students' awareness of SWs) contributed to this ranking. The study also suggests that writing studies professionals (teachers, writing centre staff) and the publishing industry include signal words as part of a hybrid (quantitative-qualitative) exploration when considering the difficulty of model essays in anthologies.