Background: Dutch youth health care promotes four so-called energy-balance behaviours for the prevention of obesity: increasing physical activity, reducing sedentary behaviour and sugar-containing drinks, and eating breakfast. However, data on the prevalence of these behaviours and intentions to engage in them among primary schoolchildren is limited, especially for multi-ethnic, inner-city populations. The present study aimed to provide these data and explore differences according to socio-demographic characteristics and weight status. Methods: Data on behaviours and accompanying intentions were collected using classroom questionnaires. Stature and body weight were measured by trained staff. Twenty primary schools in Rotterdam participated. Data on 1095 9-12 year olds (81.7% response rate) were available for analysis. Multiple logistic regression analyses were conducted to determine associations between behaviours (favourable or unfavourable), intentions (positive or not), gender, age, ethnicity, neighbourhood income level and weight status. Results: The prevalence of being overweight was 30.4%, including 9.0% obesity. Engagement in energy-balance behaviours varied from 58.6% for outdoor play (> 1 h previous day) to 85.9% for active transportation to school (day of survey). The highest positive intentions were reported for taking part in sports (83.9%), and lowest for reducing computer time (41.3%). Small differences in behaviours and intentions according to socio-demographic characteristics were found, most notably a lower engagement in physical activity by girls. Skipping breakfast and total number of energy-balance behaviours were associated with being overweight. Conclusions: The prevalence of being overweight among Dutch inner-city schoolchildren is high. A general rather than a differentiated approach is needed to improve engagement in energy-balance behaviours among inner-city schoolchildren.