Latent growth curve modelling was used to contrast the developmental trajectories of hyperactivity-inattention (H-I) problems across childhood for children with a language difficulty at the start of school and those with typical language and to examine if the presence of a language difficulty moderates the associations of child, parent and peer predictors with these trajectories. Unconditional and language-status conditional latent growth curves of H-I problems were estimated for a large nationally representative cohort of children, comprising 1627 boys (280 – language difficulty) and 1609 girls (159 – language difficulty) measured at age 4 to 5, 6 to 7, 8 to 9 and 10 to 11. Multiple regression tested interaction between language status and predictors of the level and slope of the trajectory of H-I problems. On average, boy’s H-I behaviours showed temporal stability while for girls H-I decreased over time with a slower rate of decrease with age. For both boys and girls, the levels of H-I problems were persistently elevated for those with a language difficulty compared to their peers. Neither the shape nor rate of change of H-I problems were associated with language status. Child sociability predicted the rate of growth in H-I for boys with a language difficulty but not for other boys. Child prosocial behaviours and parental psychological distress predicted the rate of growth in H-I for girls with a language difficulty but not for other girls. Parental hostility was associated with the rate of growth only for boys with typical language. The findings indicate that having a language difficulty at school entry is associated with persistently higher levels of H-I problems across childhood and moderates the rate of their growth in some circumstances.