Many forms of unhealthy behaviour are more frequent in the lower socio-economic groups. This study aims at assessing the effectiveness of a 'community-based intervention' to reduce smoking, excessive alcohol consumption, lack of physical exercise and fat consumption among joung adults in deprived neighbourhoods in Rotterdam. The intervention program will consist of tailored health promotion (based on the Attitudes-Social norms-Efficacy-model) and intersectoral action (to create an environment conducive to behavioural change). Eight neighbourhoods will be assigned at random to the intervention program or the control condition (business as usual). Measurements will include both process and outcome indicators, and data will be collected in panel surveys, repeated cross-sectional surveys, and with local agencies. The results will be analysed in a multilevel framework, with adjustment for differences between neighbourhoods in base-line characteristics.