The success of environment-friendly packages is highly dependent on consumers' understanding and acceptance of these packages. In an experiment using a 3 × 2 between-subject design, this study tests how style elements (i.e. the material and the colour) influence perceptions of packaging environment-friendliness when an environmental claim is either absent from or displayed on the package. Next, the study tests the effects of the style elements and environmental claim on the evaluation of the social responsibility of the brand as well as on the inferences about product environment-friendliness. Based on the responses of 207 participants from a Dutch consumer panel, the results show that the style elements and environmental claim influenced both the evaluations of packaging eco-friendliness and the social responsibility of the brand. When an environmental claim about the package was displayed on the package, the results show that the material is worth a thousand words as the credibility of the claim was always significantly higher when the package was made of a fibre-based material. Finally, the effect of the material on the inferences about product environment-friendliness is underlined and implications for designers, managers and policy-makers are highlighted.