Longitudinal data (five waves) from large cohorts of 7th grade students in East Germany ("n"=2,119) and West Germany ("n"=1,928) were collected from the start of the reunification of the school systems following the fall of the Berlin Wall. Here we integrate the two major theoretical models of relations between academic self-concept and achievement. In support of the reciprocal effects model, prior self-concept and prior achievement had significant effects on subsequent self-concept and subsequent achievement. In support of the internal/external frame of reference model, math achievement had a positive effect on Math self-concept but a negative effect on German self-concept, whereas German achievement had a positive effect on German self-concept but a negative effect on Math self-concept. Consistent with the unification of these models, prior self-concept in each school subject had positive effects on achievement in the same subject, but negative effects of achievement in the other school subject. Multigroup structural equation models demonstrated that all predictions were supported for both East and West German students.