This dissertation provides an account of evidentiality of a number of selected verbs of perception in Modern Standard Arabic (MSA). The verbs are divided into three categories: activity, experiential, and source-based, following Viberg (1983). The data shows that the activity P.Vs in MSA are rarely used evidentially whereas the experiential and the source-based ones are commonly used to indicate evidential meaning. It also shows that while the source-based verb is mostly used with an inferred evidential meaning, the evidentiality encoded by the experiential perception verbs is determined by the complementation pattern and the person of the subject (first or third person subject). With the non-finite complement, these verbs indicate a direct evidentiality when having a first person subject, and a reported evidentiality when having a third person subject. With the finite CP complement, they indicate an indirect evidentiality. This corpus-based study also examines the grammaticalization of these verbs when used evidentially. I argue that only the verb ra’aa of the selected experiential verbs is fully grammaticalized, but only when it is in the past tense and followed by a verbal non-finite complement. In this usage, it becomes a light verb. The source-based verb badaa/yabduu when indicating an evidentiality, it is grammaticalized into copulative verb when followed by an adjectival predicate, and modal verb when followed by a finite complement.