ABSTRACT Promoting positive development may lead to young people’s active contributions to their environment through positive attitudes and behaviours. The Climate Change Attitude Survey (15-item version) aims to identify climate change attitudes differences in groups of students and to assess pre- to post-intervention attitude changes. We intended to validate and test a possible extension of this scale among a Portuguese sample of adolescents and emerging adults. We also investigated whether higher scores on this scale would be positively associated with positive youth development. Exploratory and confirmatory factor analysis, measurement invariance, and convergent validity were assessed. The results showed good psychometric properties aligned with the original factorial structure. Significant differences were found among female and male samples regarding beliefs and intentions. A small but significant positive association was identified with a positive youth development scale. We suggest this may be an adequate instrument to assess youth climate change beliefs and intentions.