This paper presents the results of a project designed to functionally test the mutual intelligibility of spoken Maltese, Tunisian Arabic, and Benghazi Libyan Arabic. We compiled an audio-based intelligibility test consisting of three components: a word test where the respondents were asked to perform a semantic classification task with 11 semantic categories, a sentence test where the task was to provide a translation of a sentence into the respondent’s native language, and a text test where a short text was listened to twice and the respondents were asked to answer 8 multiple-choice questions. Data were collected from 24 respondents in Malta, Tunis, and Benghazi. It was found that there exists asymmetric mutual intelligibility between the two mainstream varieties of Maġribī Arabic and Maltese, with speakers of Tunisian and Libyan Arabic able to understand about 40 % of what is being said to them in Maltese, against about 30 % for speakers of Maltese exposed to either variety of Arabic. Additionally, it was found that Tunisian Arabic has the highest level of mutual intelligibility with either of the other two varieties. Combining the intelligibility scores with comparative linguistic data, we were able to sketch out the phonological variables involved in enabling and inhibiting mutual intelligibility for all three varieties of Arabic and set the stage for further research into the subject.