The paper examines two types of texts, personal experience narratives and expository discussions, dealing with the shared theme of interpersonal conflict. Both were produced by the same 80 subjects, participants in a crosslinguistic study on developing literacy: gradeschoolers aged 9;0 to 10;0, twelve-to-thirteen-year-old junior high school students, sixteen-to-seventeen-year-old high school students, and graduate-level university students. The study reported here aims to demonstrate that inter-genre differentiation is evident from an early age and is reflected by distinct forms of expression across different interlocking linguistic systems. In keeping with the focus on relations between linguistic forms and discourse functions that motivates our study, we further aim to show how particular grammatical elements can fulfil different discourse functions across development. To this end, we analysed several different lexical and morphosyntactic constructions in 160 Hebrew-language texts as diagnostic of inter-genre distinctiveness: subjectless constructions; verbless copular clauses; verb types and the temporal categories of verb tense and mood, including lexical expressions of modality in the two genres. Results show that narratives are clearly distinguished from expository texts along all these dimensions; these distinctions are evident from the youngest age group we considered; and with age, inter-genre differentiation emerges as more moderately dichotomous. We concluded from this that maturely proficient text construction is able to combine expository-type generalizations with narrative event-description and to intersperse narrative-type illustrative episodes with expository formulation of ideas.