In this article, existing research investigating how school performance relates to cognitive, self-awareness, language, and personality processes is reviewed. We outline the architecture of the mind, involving a general factor, g, that underlies distinct mental processes (i.e., executive, reasoning, language, cognizance, and personality processes). From preschool to adolescence, g shifts from executive to reasoning and cognizance processes; personality also changes, consolidating in adolescence. There are three major trends in the existing literature: (a) All processes are highly predictive of school achievement if measured alone, each accounting for ∼20% of its variance; (b) when measured together, cognitive processes (executive functions and representational awareness in preschool and fluid intelligence after late primary school) dominate as predictors (over ∼50%), drastically absorbing self-concepts and personality dispositions that drop to ∼3%-5%; and (c) predictive power changes according to the processes forming g at successive levels: attention control and representational awareness in preschool (∼85%); fluid intelligence, language, and working memory in primary school (∼53%); fluid intelligence, language, self-evaluation, and school-specific self-concepts in secondary school (∼70%). Stability and plasticity of personality emerge as predictors in secondary school. A theory of educational priorities is proposed, arguing that (a) executive and awareness processes; (b) information management; and (c) reasoning, self-evaluation, and flexibility in knowledge building must dominate in preschool, primary, and secondary school, respectively. (PsycInfo Database Record (c) 2023 APA, all rights reserved).