This study reports developmental changes in morphological encoding across late childhood. We examined event-related brain potentials (ERPs) during the silent production of regularly vs. irregularly inflected verb forms (viz. -t vs. -n participles of German) in groups of eight- to ten-year-olds, eleven- to thirteen-year-olds, and adults. The adult data revealed an enhanced (right-frontal) negativity 300–450 ms after cue onset for the (silent) production of -t relative to -n past participle forms (e.g. geplant vs. gehauen ‘planned’ vs. ‘hit’). For the eleven- to thirteen-year-olds, the same enhanced negativity was found, with a more posterior distribution and a longer duration (=300–550 ms). The eight- to ten-year-olds also showed this negativity, again with a posterior distribution, but with a considerably delayed onset (800–1,000 ms). We suggest that this negativity reflects combinatorial processing required for producing -t participles in both children and adults and that the spatial and temporal modulations of this ERP effect across the three participant groups are due to developmental changes of the brain networks involved in processing morphologically complex words.