Definition:
Separate Underlying Proficiencies (SUP) is the hypothesis that a bilingual person’s languages develop in completely independent compartments, with no cognitive or academic transfer between them. Under SUP, time and effort invested in one language would have zero benefit for the other — each language would need to be built from scratch.
In-Depth Explanation
SUP is primarily discussed as the foil to Jim Cummins‘ Common Underlying Proficiency model. Cummins articulated the SUP position to make the opposing view explicit: if languages develop separately, then bilingual education programs that use L1 instruction are wasting time that could be spent on L2.
The SUP model predicts that a child who is literate in Spanish but studying in an English-medium school gains nothing academically from their Spanish literacy — they’d need to develop English academic skills entirely independently. This prediction has been consistently contradicted by research. Studies of bilingual education programs, heritage speakers, and immigrant children show significant cross-linguistic transfer of reading skills, academic strategies, and conceptual knowledge.
SUP’s practical legacy is in the policy arguments it inspired. “English-only” education policies in the US (such as California’s Proposition 227 in 1998) were implicitly based on SUP logic: the assumption that time spent in L1 instruction subtracts from L2 development. Research evidence overwhelmingly favors CUP, and SUP is now considered a discredited model in applied linguistics.
Common Misconceptions
“SUP is a mainstream theory.”
SUP was never widely supported by researchers. Cummins articulated it mainly as a contrast to CUP — to name the assumption that policymakers were implicitly operating under without empirical support. Most applied linguists have accepted CUP since the 1980s.
Related Terms
See Also
Research
- Cummins, J. (1981). The role of primary language development in promoting educational success for language minority students. In Schooling and Language Minority Students: A Theoretical Framework (pp. 3–49). California State Department of Education. — The paper where CUP and SUP are contrasted most explicitly.