SummaryAttempts to mitigate the environmental impact of oil-palm expansion by improving production standards have been of limited success. An alternative approach aims at a better understanding of the factors that drive consumers to reduce excessive vegetable oil consumption. Our studies focused on consumers’ environmental knowledge as a potential determinant of palm oil consumption. They revealed critical limitations in consumers’ palm oil-related knowledge across different domains, study settings and assessment approaches. The more our participants knew about palm oil and its environmental consequences, the stronger were their reported intentions to reduce their consumption. This relationship was significantly stronger for subjective versus objective palm oil-related knowledge. In addition, we examined whether consumers can be stimulated to consult information about palm oil by making information access the default option. While this simple situational nudge promoted information access, we did not find it to significantly increase actual engagement with the information material. This result suggests that it might be necessary to complement default nudges for information access with other measures to enhance palm oil-related knowledge and to reduce palm oil consumption to more sustainable levels.