This article deals with the different values of the verb kāna in contemporary Arabic. Out of a non dialectal contemporary Arabic corpus of 1.5 million words, I have studied and categorized more than 15,000 occurrences of the verb kāna. My goal is to make a list of its main values (be they modal, temporal, aspectual or pragamatic) and highlight the syntactic functioning of this verb. For each case I will analyse a representative example. The modal value of possibility, as ruled by the verb kāna, will be the object of specific attention. I will compare this inventory to the descriptions of the verb kāna in modern Arabic language grammar books, so as to assess how adequate their descriptions are. An explanatory model will also be offered, which allows to integrate all the values of kana into one single model for its syntactic functioning.