The validity of the Multidimensional School Anger Inventory (MSAI) was examined with adolescents from 5 Pacific Rim countries (N = 3,181 adolescents; age, M = 14.8 years; 52% females). Confirmatory factor analyses examined configural invariance for the MSAI's anger experience, hostility, destructive expression, and anger coping subscales. The model did not converge for Peruvian students. Using the top 4 loaded items for anger experience, hostility, and destructive expression configural invariance and partial metric and scalar invariances were found. Latent means analysis compared mean responses on each subscale to the U.S. sample. Students from other countries showed higher mean responses on the anger experience subscale (ds = 0.37-0.73). Australian (d = 0.40) and Japanese students (d = 0.21) had significantly higher mean hostility subscale scores. Australian students had higher mean scores on the destructive expression subscale (d = 0.30), whereas Japanese students had lower mean scores (d = -0.17). The largest latent mean gender differences (females lower than males) were for destructive expression among Australian (d = -0.67), Guatemalan (d = -0.42), and U.S. (d = -0.66) students. This study supported an abbreviated, 12-item MSAI with partial invariance. Implications for the use of the MSAI in comparative research are discussed.