With this article I explore the relationship between core academic language skills (CALS) -- a construct representing a set of high-utility language skills needed to manage the linguistic features prevalent in academic texts across content areas -- and schooling outcomes. There has long been an understanding that there is a distinction between academic language and colloquial language, originally described by Jim Cummins (1976) as cognitive academic language proficiency (CALP) and basic interpersonal communication skills (BICS). The construct has only recently been operationalised (Uccelli, Phillips Galloway, Barr, Meneses & Dobbs, 2015) as the individual skills and competencies that underlie CALP. The CALS construct describes an empirically testable set of competencies that address this need. This has been used in the development of an assessment instrument aimed at South African learners -- the CALS-I-ZA (MacFarlane, Barr & Uccelli, 2022) -- and I investigate whether a measurable link exists between this assessment and schooling outcomes for a sample of Grade 6 learners in 2 public schools in the Gauteng province of South Africa. Schooling outcomes have been measured using the Gauteng Provincial Common Assessments -- a provincial examination intended to measure schooling outcomes on a comparable assessment instrument. The study reported on here shows a moderately strong correlation between the CALS-I-ZA and the provincial common examinations (r = 0.64 and r = 0.65). This predictive relationship between CALS and schooling outcomes leads to an argument for direct instruction in CALS as an embedded feature of pedagogy in South Africa.