Climate change is a widely debated issue in the 21st century and thanks to the use of social media platforms, the ongoing wave of protest action has engaged many young environmental activists who have contributed to make this issue a global one (Boulianne, 2022). As a result of Greta Thunberg's protests in 2018, a great deal of new research in social sciences has been carried out in the wake of the European youth climate activist movement (Belotti et al., 2022; de Moor et al., 2021). Many scholars investigated youth climate movements through Instagram posts in Linguistics and Communication research. However, most studies have mainly focused on hashtag-based data (Herrmann et al., 2022) or on accounts of single activists, such as Greta Thunberg (Molder et al., 2021). This work complements previous research by addressing youth climate movements’ communication in three European countries. Specifically, we compare how the content of messages posted on Instagram from 2020 to 2022 by the Italian Fridays For Future, and Youth for Climate in France and Belgium, is framed, and also analyze the reactions to these messages. Moreover, the use of Instagram by youth climate movements in the three countries is also discussed. From the methodological point of view, this research presents the results obtained through a multimodal framing analysis to detect the thematic frames based on differences and similarities of youth activist groups in three countries. In addition, climate-related terms and collocations are analyzed by corpus linguistic techniques with the use of Sketch Engine. Finally, the polarity of comments in response to their messages are investigated by an automated sentiment analysis. The present mixed approach will contribute to better understand these European movements and their audiences. Due to cultural and societal differences, the results in France and Belgium are expected to differ from those in Italy.