The developmental interdependence hypothesis: L2 competence depends partly on L1 competence at the onset of intensive L2 exposure¶

Theory · All theories
Evidence · 7 claims (5 for, 2 mixed) · 4 studies (2 associational, 1 review, 1 theoretical), q1–q3 · 0 of 4 report an effect size · 7 claims rest on one study

Description¶

The developmental interdependence hypothesis is the paper's central explanatory account of how first-language (L1) and second-language (L2) skills relate across development. It proposes that "the development of competence in a second language (L2) is partially a function of the type of competence already developed in Ll at the time when intensive exposure to L2 begins." When a child's L1 is well developed before intensive L2 exposure, high L2 competence can develop at no cost to L1; when L1 is less developed, early intensive L2 exposure impedes continued L1 growth, which in turn limits L2 development. The hypothesis underpins the paper's argument that instruction through the minority child's L1 supports, rather than hinders, L2 acquisition.

Design Implications¶

Context¶

Requirements¶

The child's L1 must have developed certain functions (vocabulary-concept knowledge, literacy prerequisites) prior to intensive L2 exposure for transfer to support L2 learning

Constraints¶

The hypothesis addresses functional interdependence between L1 and L2 skill development; the paper states it does not specify which school programs promote additive versus subtractive bilingualism under all conditions

Target Learners¶

Bilingual children, including minority-language and majority-language children in bilingual or immersion programs

Target Learning Objectives¶

Second-language competence
First-language maintenance and development
Academic achievement in bilingual education programs

Claims¶

L1 Maintenance Supports L2 Without Cost [+M]
Mother Tongue Preservation Predicts L2 Achievement [+M]
Native signers of ASL show more proficient bilingual abilities than non-native signers [+M] — attached 2026-10-16 from Freel et al. (2011), which proposed "Linguistic Interdependence Theory applied to deaf bilingual education"; tests this page's relationship.
Growth in Spanish receptive language during Head Start predicts first-grade English letter-word identification and passage comprehension, with timing-of-exposure group differences for Spanish vocabulary [+W] — attached 2026-10-17 from Davison et al. (2011), which proposed "Common Underlying Proficiency (CUP) model of bilingual language and literacy development"; tests this page's relationship.
Small-scale studies suggest age 15-16 with intermediate English proficiency (reading GE 5) is a good immigration age [~W]
Timing of English exposure moderates how vocabulary growth predicts reading: English vocabulary growth predicted HEC children's English passage comprehension while Spanish vocabulary growth predicted SEC children's English reading [~W]
Youngest-arriving ESL learners risk acquiring neither L1 nor L2 at the level school demands [+W]

Examples¶

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Key Sources¶

Cummins, James. (1979). Linguistic interdependence and the educational development of bilingual children. https://eric.ed.gov/?id=ED257312. doi:10.3102/00346543049002222

Page metadata

Field	Value
`type`	`theory`
`title`	`The developmental interdependence hypothesis: L2 competence depends partly on L1 competence at the onset of intensive L2 exposure`
`description`	`The developmental interdependence hypothesis is the paper's central explanatory account of how first-language (L1) and second-language (L2) skills relate across development.`
`status`	`review`
`canonical`	`True`
`generated`	by `claude/unspecified` on `2026-09-25`
`trust`	unverified — no one has confirmed this page's content
`sources`	1 — `cummins-1979`

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