This study investigated the extent to which results of rhetorical comparisons of persuasive essays by Moroccan students learning English as a foreign language (EFL) would provide empirical evidence for Kaplan‘s (1966) contrastive rhetoric hypothesis. This is especially regarding the fact that EFL students-writing problems are a byproduct of negative transfer of rhetorical strategies from their first language (L1). This hypothesis was tested by comparing 52 EFL and Arabic L1 persuasive essays by the very same EFL students to identify whether or not the language of composing affected the writing quality of their essays. The study hypothesizes that if Kaplan‘s contrastive rhetoric claims were accurate, then Moroccan advanced EFL writers would produce essays that tend to be rhetorically less accurate when judged by standard English rhetorical criteria. Prior to their use in the current study, the validity of the analytical measures was established by exploring if the participants’ rhetorical performance would predict the overall quality of their essays. While the results of a stepwise multiple regression analysis provided further evidence corroborating the validity of the rhetorical measures used in the study, group mean scores comparisons and a multiple discriminant analysis of the data indicated that there are more similarities than differences in the EFL and AL1 essays of the study  participants.