Although previous meta-analyses (Crocetti et al., 2021; Raabe & Beelman, 2011) have found that prejudice remains stable during adolescence, there may be individual differences in prejudice levels and developmental trajectories that deserve further investigation (Crocetti et al., 2021). The present study aims to further the understanding of how ethnic prejudice (considering both its cognitive and affective dimensions) develops in the transition from late adolescence to emerging adulthood. Participants were 297 (Mage = 17.48, SDage = 0.79, 37.8% males) of 11th- and 12th-grade students attending High Schools in the North-East of Italy. Informed consent was collected from participants and their parents. Data collection consisted of five waves with a three-month interval between the first three time points (November 2016, February 2017, and May 2017) and a one-year interval between the last two time points (May 2018 and May 2019). At each time point, participants completed a questionnaire comprising measures of identity, attitudes, and well-being as part of a larger longitudinal study. The present investigation will focus exclusively on cognitive and affective prejudice and educational identity measures, together with individual and family demographics (i.e., gender, parental education).