Abstract Identification with the European group bears important implications for adjustment, intergroup processes, and civic participation. However, little is known about its development across different time scales in adolescence. The current study examined short- and medium-term developmental trajectories of European identification across two age cohorts separately and conjointly. Participants were 1552 Italian adolescents (M age = 15.69, SD age = 1.22; 47.04% females) attending the 1st (52.30%) and 3rd (47.70%) year of high school. Results highlight general stability in the short- and medium-term, although younger and older adolescents differed in their developmental patterns. Youth’s age and short-term fluctuations in European identification were linked to unique medium-term trajectories. This research highlights the importance of combining social and developmental approaches to comprehensively study how social identification unfolds in adolescence.