Purpose – This paper investigates why and when messages regarding unsustainable luxury products lead to negative word-of-mouth (NWOM) through a focus on the role of guilt, need to warn others and consumers’ cultural orientation. Design/methodology/approach – Three experiments test whether messages describing unsustainable versus sustainable luxury manufacturing processes elicit guilt and a need to warn others and whether and how the need to warn others affects consumers’ NWOM depending on their cultural orientation. Findings – Consumers experience guilt in response to messages emphasizing the unsustainable (vs sustainable) nature of luxury products. In turn, guilt triggers a need to warn other consumers, which leads to NWOM about the luxu...