This paper outlines functionally motivated quantifiable criteria for characterizing different facets of discourseglobal-level principles, categories of referential content, clause-linking complex syntax, local linguistic expression and overall discourse stancein relation to the variables of development, genre and modality. Concern is with later, school-age language development, in the conviction that the long developmental route of language acquisition can profitably be examined in the context of extended discourse. Findings are reviewed from a cross-linguistic project that elicited narrative and expository texts in both speech and writing at four age groups: (910 years, 1213, 1617 and adults). Clear developmental patterns emerge from middle childhood to adulthood, with significant shifts in adolescence; global-level text organization is mastered earlier in narratives than in expository essays, but the latter promote more advanced use of local-level lexicon and syntax; and spoken texts are more spread out than their denser written counterparts in clause-linkage, referential content and lexical usage. These and other findings are discussed in terms of the growth and reorganization of knowledge about types of discourse and text-embedded language use.