Positive socioemotional outcomes and developments represent important educational goals. Full-time ability grouping of gifted students has been criticized for potentially detrimental socioemotional effects. Therefore, in the present longitudinal study, we investigated whether or not social self-concepts and school-related attitudes and beliefs are affected by full-time ability grouping of the gifted. Students in regular classes and students in special classes for the gifted were paralleled for cognitive ability, sex, socioeconomic status, and school. By doing so, we studied 99 "statistical twins" ("N" = 198) from the beginning of fifth grade to the middle of sixth grade. Data were analyzed through repeated-measures multivariate analysis of covariance (within-subject factor: time; between-subject factors: class type--gifted vs. regular--and cognitive ability as covariate). Cognitive ability had hardly any effect on the variables under study. Attending a gifted class had initially positive effects on students' social self-concept of acceptance but no effects on social self-concept of assertiveness. Moreover, children in gifted classes exhibited more interest in school and reported better student-teacher relationships than their counterparts in regular classes.