It has been found that bilinguals and children from minority backgrounds, lag behind monolinguals or those in the majority culture, with respect to prevalence, assessment, and treatment for Attention Deficit/Hyperactivity Disorder (ADHD). This suggests that bilingualism might be yet another factor giving rise to variability in ADHD. Using regression methods, we analysed parent reports for 394 primary school-aged children on background and language experience, ADHD-related behaviour, and structural language skill in English to explore whether bilingualism is associated with levels of ADHD-related behaviour. Bilingualism as a category was associated with slightly lower levels of ADHD-related behaviour. Bilingualism as a continuous measure showed a trend of being associated with lower levels, but this did not quite reach significance. Structural language skill in English was the main predictor of levels of ADHD-related behaviour; higher skill predicting lower levels. More investigation is required to confirm whether these effects occur across different populations, to understand which if any aspects of bilingualism give rise to variability, and if need be, to address these as far as possible.