The process of learning a second or foreign language that is different from one's native language can often be challenging. Among the various difficulties that can arise within this process, one seems to be transversal and occurs very frequently when an adult speaker of an article-less language learns a second language with articles. Articles are among the most commonly used words in many languages, such as English, and the omission or incorrect use of articles can seriously affect communication in many cases. This subject has been approached differently by various scholars, who have proposed different models to explain the phenomenon. The aim of this article, therefore, is therefore to review different perspectives on the acquisition of articles by adult learners speaking L1 article-less languages. After a brief introduction to the key concepts, the twelve main hypotheses on article acquisition by L1 article-less adult learners are presented and discussed in chronological order. Both the most widely accepted hypotheses in the literature at present (e.g. the Fluctuation Hypotehesis) and the various hypotheses that have contributed significantly to the development of the different theories, such as Huebner's preliminary studies, are considered. By means of a chronological digression, it will thus be possible to obtain an overview of the state of the art of theories on the acquisition of L2 articles by native speakers of languages without articles.