In Dutch L1 classrooms, style in non-fictional genres is typically taught by means of normative exercises in which students are tasked to identify stylistic lapses. Not much is known about the effectiveness of such exercises when teaching style. Unknown factors include what kinds of stylistic shortcomings are found in Dutch students’ writing, and how the occurrence of certain stylistic lapses relates to writing quality. The current study empirically explores these scarcely investigated issues. Teachers rated 125 argumentative texts written by tenth-grade pre-university students by means of comparative judgement. Additionally, these texts were manually analyzed to investigate the occurrence of stylistic lapses, taking into account stylistic lapses that are common in text books (‘standard category’) and other types of style related errors (‘other category’). Multilevel regression analyses revealed that only one of the stylistic lapses from the standard category negatively influenced text quality as evaluated by teachers, namely the use of detached phrases. In the other category, only mistakes in question marks negatively predicted text quality. A final model including those two predictors explained 11.1% of the variance in text quality. The article discusses the implications of these findings for non-fictional style education, suggesting that it might need to be refocused.