Language disorder (LD) and social-emotional and behavioural (SEB) difficulties are common childhood problems that often co-occur. While there is clear evidence of these associations from clinical samples, less is known about community samples. This paper examines these associations in children aged 4–7 years from a community-based longitudinal study. 771 families provided questionnaire and assessment data at 4, 5 and 7 years. Parent-reported SEB difficulties were measured at each point (SDQ). Child language was directly assessed at 4 (CELF-P2), 5 and 7 years (CELF-4). Linear regression analysis was used to compare cross-sectional differences in mean SDQ scores between children with and without LD at each time point. Linear regression was then used to examine how patterns of language development (language disordered at three time points; never disordered; disordered at one or two time points, i.e. ‘unstable’ group) related to SEB difficulties at each age, adjusted for potential confounders, as in the previous analyses. Higher hyperactivity/inattention scores were associated with LD at each age. In fully adjusted models, there was little difference in mean emotional symptoms scores between children with and without LD. The ‘never’ LD group had lower mean SDQ scores at each time point than the ‘unstable’ group. Findings highlight that children with persistent LD from preschool to early primary school may be more likely to have concomitant SEB difficulties, particularly behavioural difficulties. Those with unstable LD may also have co-occurring SEB difficulties, showing a need for education and health professionals to monitor early language and SEB development.