The reciprocal internal/external frame of reference model (RI/EM) combines the internal/external frame of reference model and the reciprocal effects model. The RI/EM predicts positive effects of mathematics and verbal achievement and academic self-concepts (ASC) on subsequent mathematics and verbal achievements and ASCs within domains and negative effects of mathematics and verbal achievements and ASCs on subsequent achievements and ASCs across domains. Although ample support was provided for the I/E model by cross-sectional data and for the REM within a single domain, there has been almost no research on the longitudinal generalizability of the reciprocal cross-domain effects. Using three waves of data collection from Grade 5 to Grade 8 with N = 1,508 students, analyses supported the validity of the RI/EM, revealing positive longitudinal effects of grades and ASCs on subsequent grades and ASCs within domains and negative effects of grades on subsequent ASCs across domains. There were also small negative effects of ASCs on subsequent grades across domains. (Contains 2 notes, 4 tables, and 3 figures.)