Most English-as-a-second-language (ESL)/ English-as-a-foreign-language (EFL) teachers would agree that modal verbs remain difficult notions to teach. While intermediate to advanced ESL/ EFL students manifest sufficient command of form, they invariably struggle with using English modals in pragmatic and meaningful ways. With regard to Arab EFL learners’ acquisition of modal verbs, several studies have investigated the issue (e.g. Elenizi, 2004; Saeed, 2009; Sabri, 2011). However, none of the previous research endeavors has tried to study Arab learners’ difficulties with modal verbs outside of EFL contexts, nor have they explored how ESL/EFL textbooks deal with modality and Arab learners. Thus, this paper attempts to examine the nature of Arab ESL learners’ difficulties with modal verbs in English and the inadequacies of ESL textbooks in this regard. Thereby, it analyzes modal verbs from the lenses of reference grammar books and also from the lenses of ESL student grammar textbooks, and it also puts forward some suggestions on how to approach the Arab students’ challenges with English modal verbs.