This study focuses on the national identity of high-school adolescents in Russia and Ukraine in the post-perestroika period. Adolescents studying in public high schools in 12 medium-size and large cities completed questionnaires in 1999 (n = 468) and 2007 (n = 646). Russian adolescents consistently reported a more positive attitude towards their country and a stronger identification with the nation than did Ukrainian adolescents. The effect of socio-economic changes on the two components of national identity differed: the adolescents reported a more positive attitude towards their country in 2007 than in 1999, while their identification with the nations did not change significantly. Social support received from peers was associated with a more positive attitude towards the country and a stronger identification with the nation, while social support received from parents and teachers was not related to the national identity of adolescents. Adolescents' better psychological adjustment was associated with a more positive attitude towards the country but was not related to their identification with the nation. Adolescents who belonged to the ethnic majority reported a more positive attitude towards the country and a stronger identification with the nation as compared to adolescents who belonged to ethnic minorities.