The paper examines the nominal lexicon in later language acquisition as a window on linguistic knowledge and usage across childhood and adolescence. The paper presents a psycholinguistically motivated and cognitively grounded analysis of the distribution of ten semantic noun categories (the Noun Scale) across development, modality, and genre. Eighty Hebrew-speaking children (9;0 to 10;0), adolescents (12;0 to 13;0 and 16;0 to 17;0), and a group of adult university graduate students participated in the study. Each produced four different texts: a spoken and written narrative and a spoken and written expository, yielding a total of 320 texts. All lexical noun tokens in each of the 320 texts were analyzed to determine their score on the Noun Scale. Results indicate that nominal density, which underlies much of the syntactic architecture of texts, increases dramatically in adolescence, towards adulthood. The paper analyses the developmental patterns of each of the ten Noun Scale categories, showing that the nominal lexicon of schoolaged children is already very different from that of young children in having only a small amount of genuinely concrete nouns, and these too only in narrative texts. The quantitative analysis shows that nouns grow more categorical and abstract with age and schooling, especially in adolescence. Written expository texts are the preferred habitat of abstract, categorical nouns from early on. The systematic qualitative analysis of noun tokens in their textual context demonstrates how the nominal lexicon undergoes fundamental changes that are affected by linguistic, cognitive and social development, in interaction with text genre and modality.