This article studies the derivational system of gender and number in Ait Atta variety of Amazigh language. Thus, the following claims are made: first, gender is overtly marked on feminine nouns by the prefixation of the gender morpheme t-. The paper argues that [t…t] is not a circumfix or a discontinuous morpheme, but it is an asymmetric inflection. In the derivational system of gender, large majority of nouns allow for gender opposition. However, mass nouns allow only for one lexically determined gender and number. Moreover, masculine has no overt realization in Amazigh language. Vocalic initial nouns fall into the category of masculine nouns. I argue that the initial vowel is a nominal marker. I submit that the noun, in general, consists of maximally three main parts: a prefix, a lexical base, and a suffix. Second, the majority of Berber noun stems involve, at least, one vowel in addition to the prefixal vowel (e.g. ‘a-ḍar’ foot, ‘a-funas’ bull, 'a-ɣrum’ bread). Third, when the plural noun is specified as [+feminine], it takes the gender morpheme t-. Fourth, number takes the form of a feature assigned lexically to the noun. The study provides a templatic analysis to account for internal noun change. It implements Lahrouchi and Ridouane (2016) analysis of diminutives and plurals in Moroccan Arabic and argues that sound plurals in Amazigh language are associated with standard Num projection, while id/istt-plurals are associated with lower in the structure with n projection.