Purpose: Unhealthy eating among adolescents from families with lower social status is a major concern. The purpose of this paper is to describe the development and evaluation of a prototype-targeting intervention for the promotion of healthy eating in this target group. Design/methodology/approach: The planning model intervention mapping (IM) was chosen to proceed systematically, to use theory and evidence herein and to make decisions transparent. A controlled study with three times of data assessment was conducted to evaluate process characteristics and effects (N=108). Findings: "Provide opportunities for social comparison" (behavioural change technique 6.2) was chosen as change method and "perceived similarity" was identified as the condition for its effectiveness. An intervention unit was designed for application. The evaluation results show the feasibility of the unit; materials and activities successfully applied the change method and its condition for effectiveness; and intervention objectives were generally achieved. Practical implications: A prototype-targeting intervention is provided that is based on theory and evidence, and is suitable for implementation. More generally, the paper can serve as a blueprint for the systematic planning of theory- and evidence-based interventions targeting specific personal determinants for behaviour change. Originality/value: The paper makes an important contribution to the application of the prototype-related theory and a useful addition of IM to the growing field of intervention development and design.