This study examined developmental trajectories of social justice values (SJV) in a representative sample of Swiss adolescents (N = 1258) at 15 (Time 1), 18 (Time 2), and 21 years of age (Time 3). SJV and friendship quality were measured via self-reports. Sympathy was assessed via self- and mother-reports. Latent class growth analysis revealed three developmental trajectories of SJV: high-stable (80 percent), moderate-decreasing (17 percent), and low-increasing (3 percent). Adolescents with low levels of self- and mother-reported sympathy were more likely to be members of the low-increasing than the high-stable or moderate decreasing trajectory groups. Adolescents who reported low levels of sympathy and friendship quality at 15 years of age were more likely to be members of the moderate-decreasing trajectory group than the high-stable trajectory group. Results are discussed with respect to the potential significance of sympathy and friendship quality for understanding the development of SJV during adolescence.