Marking the point of departure of the clause, Theme position is used to identify subject matter, the writer’s angle on that subject matter, and the direction of travel of the text. Learning to exploit this cohesive resource is essential to the learning-to-write process, becoming increasingly relevant in late childhood as children begin to write longer texts in a wider variety of registers. This research explores how children achieve this, by comparing texts written by 17 children aged 8-9 and 9-10 years, analyzing changes to thematization and identifying children’s “gateways” into new repertoires. Findings reveal that the writers’ choice of “macroTheme” (an overarching initial thesis statement) significantly influenced subsequent thematic choices. Furthermore, experimentation with new thematic resources reflected the writers’ adoption of a meta-perspective elicited by appropriation of modeled macroThemes, the integration of counterarguments, and recognition of the potential of abstract Themes to provide new insights into lived experience.