This paper argues that a good understanding of the behavior of schwa in Moroccan Arabic is achieved neither by considering the language independently nor by comparing it with cognate Arabic dialects. First, we point out two peculiarities associated with schwa: its being reported as an epenthetic segment only in Moroccan Arabic as opposed to other Arabic dialects, which seem to rely chiefly on the vowels [i] and [a], and its not contributing to the weight of the hosting syllable. Then, a comparative analysis of the behavior of schwa in Casablanca Moroccan Arabic and Goulmima Moroccan Amazigh is provided. It is demonstrated that the two languages share prosodic affinities regarding the prosody of schwa. We will explain this as resulting from the presence of an Amazigh substratum in the grammar of North African Arabic. Revue Langues et Littératures, Vol. 22 (2012)