Objective: To establish executive function (EF) structure/organization and test a longitudinal developmental cascade model linking processing speed (PS) and EF skills at 8-years of age to academic achievement outcomes, both at 8- and 16-years, in a large sample of children/adolescents with surgically repaired dextro-transposition of the great arteries (d-TGA). Method: Data for this study come from the 8- (n = 155) and 16-year (n = 139) time points of the Boston Circulatory Arrest Study and included WISC–III, Trail Making Test, Test of Variables of Attention, and WIAT/WIAT-II tasks. Results: A 2-factor model (Working Memory/Inhibition and Shifting) provided the best fit for the EF data, χ(3)2 = 1.581, p = .66, RMSEA = 0, CFI = 1, NNFI = 1.044). Working Memory/Inhibition and Shifting factors were not correlated. In the structural equation model, PS was directly related to both EF factors and Reading at 8 years, and was indirectly related to Math and Reading achievement, both concurrently and longitudinally, via its effects on Working Memory/Inhibition. Shifting at 8 years was significantly associated with Math (but not Reading) at 16 years. Conclusions: The academic difficulties experienced by children and adolescents with d-TGA may be driven, at least in part, by underlying deficits in processing speed and aspects of executive function. Intervention efforts aimed at bolstering these abilities, particularly if implemented early in development, may prove beneficial in improving academic outcomes and, perhaps by extension, in reducing the stress and diminished self-confidence often associated with academic underachievement.