We studied to what extent perceived adoption norms affect the likelihood of adopting sustainable innovations, next to evaluations of the instrumental, environmental and symbolic attributes of these innovations. As hypothesised, results showed that people are more likely to adopt a sustainable innovation the more they evaluate the attributes of these sustainable innovations favourably and the more they think significant others would consider adoption (i.e., when adoption norms are strong). Moreover, we hypothesised and found that positive evaluations of the symbolic attributes are more likely to promote the adoption of sustainable innovations when people expect that few significant others would consider adoption. These findings suggest that weak adoption norms that are typical in the early adoption stage may both inhibit and promote adoption of sustainable innovations, via different routes.