1st Language / 2nd Language (L1 / L2)
entry by Julie M. Marx, Global Family Expert at Expat Valley
The standard applied linguistics abbreviations for an individual’s first language (L1) and second language (L2). L1 refers to the language or languages acquired first in childhood (typically in the home environment) and L2 refers to any subsequently acquired language regardless of eventual proficiency. For internationally mobile children, the L1/L2 distinction is frequently complicated: children may acquire two languages simultaneously from birth, making the L1/L2 sequence inapplicable; dominant language shift may cause the L2 to surpass the L1 in proficiency; and heritage language may be the L1 while the language of instruction is the L2. The abbreviations are standard across all linguistic and educational literature.
Comparable terms
Mother tongue (see separate entry — widely used but contested equivalent for L1) · Heritage language (see separate entry — the culturally significant L1 in families where a shift toward L2 dominance has occurred) · Target language (language teaching — the language being learned; typically the L2 in instructed contexts) · Dominant language (sociolinguistics — the language in which a speaker has the highest proficiency; may be L1 or L2)
Why this matters
L1/L2 is the backbone of how schools and specialists talk about multilingual children. Misusing these terms can confuse assessments and interventions. Being precise about which language is which helps everyone make better support decisions.
Cross-references
BICS/CALP (Language & Identity); Heritage Language (Language & Identity); Dominant Language Shift (Language & Identity); EAL (Education). L1 and L2 are the foundational reference points for the entire Language & Identity cluster. Every other entry in that cluster (heritage language, dominant language shift, additive bilingualism, code-switching, translanguaging) is defined in relation to the L1/L2 distinction. Practitioners using these abbreviations in educational assessments, referral letters, or clinical notes should be explicit about what they mean, as “L1” is sometimes used loosely to mean “dominant language” or “home language” rather than “first acquired language” — distinctions that matter significantly for internationally mobile multilingual children.
Sources
In applied linguistics and educational terminology, L1 refers to a student’s first language (sometimes also called the home language or mother tongue) while L2 refers to subsequently acquired languages; for internationally mobile students who are often multilingual, L1 and L2 may not map cleanly onto conversational or academic proficiency.
Cummins, J. (1979). Linguistic interdependence and the educational development of bilingual children. Review of Educational Research, 49(2), 222–251. Establishes the interdependence hypothesis (that L2 academic proficiency builds on the foundation of L1 academic proficiency) making L1 maintenance a prerequisite for successful L2 academic development.
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