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Second language acquisition (SLA) is the process by which a person develops a language after their first one, and also the name of the research field that studies that process. This page gives the short definition, what each part of the term means, and one example. For the full picture, theories, stages, timelines and classroom practice, see the complete guide to second language acquisition.
Table of contents
Second Language Acquisition Definition
Quick answer: second language acquisition is the process of developing the ability to understand and use a language other than one’s first language, mainly through meaningful exposure and use rather than memorized rules. The term also names the academic field, founded as a discipline in the late 1960s and 1970s, that studies how that process works.
What Each Part of the Term Means
| Term | Meaning |
|---|---|
| First language (L1) | The language a person acquires from birth, sometimes more than one |
| Second language (L2) | Any language developed after the first, whether it is the second, third or fourth; for an English learner in a US school, English is usually the L2 |
| Acquisition | Subconscious development through understanding and using the language, as opposed to conscious learning of rules; the distinction comes from Stephen Krashen |
| SLA | The abbreviation for both the process and the research field |
The difference between the two verbs matters in practice: a student can learn a grammar rule for a quiz without having acquired it for conversation. It is explained in language acquisition vs language learning.
Second Language Acquisition in One Example
A newcomer in a first-grade class says nothing in English for two months but follows every routine. By spring she answers with single words, and by the next year with short sentences, while still saying “I goed” for “I went.” Each step, the silent period, one-word answers, and predictable errors, is second language acquisition in progress. More cases, stage by stage and theory by theory, are in second language acquisition examples.
Where to Go Next
| If you want | Read |
|---|---|
| The whole field in one place | Second Language Acquisition: A Complete Guide |
| The five stages and how long each takes | Second language acquisition stages |
| Krashen’s five hypotheses | Stephen Krashen’s theory |
| Why social English comes before academic English | BICS and CALP |
| Classroom examples | Second language acquisition examples |
Frequently Asked Questions
What is second language acquisition in simple terms?
It is how people pick up a language after their first one, mostly by understanding and using it in real communication.
What does SLA stand for?
Second language acquisition, meaning both the process and the field of research that studies it.
Does “second language” include a third or fourth language?
Yes. In SLA research, any language developed after the first counts as a second language.
Is second language acquisition the same as first language acquisition?
It shares some patterns, such as predictable orders and errors, but differs because the learner already has a first language and is usually older, and often learns partly in a classroom.
Related Resources
- Second Language Acquisition: A Complete Guide
- Second Language Acquisition Examples
- Second Language Acquisition Stages
- Language Acquisition vs Language Learning
Conclusion
Second language acquisition is the development of a language after the first, and the field that studies it. The short definition fits in a sentence; how it happens, through input, interaction, stages and years of use, is what the rest of the research explains.
Sources: Krashen, S. (1982), Principles and Practice in Second Language Acquisition; Ellis, R. (2015), Understanding Second Language Acquisition; Colorín Colorado, Language Acquisition: An Overview.
Closing the Gap Between the Science and the School Day
Every definition of second language acquisition comes back to use: learners acquire a language by understanding it and speaking it. In a class of twenty-five, each student gets only a few minutes of real conversation a day. That is the Speaking Time Gap.
Some schools add speaking practice that does not depend on class time. Telo AI is one example: five-minute sessions three times a week that adapt to each student’s level and ask follow-up questions instead of accepting one-word answers, with progress on a teacher dashboard. See how that works across a school year.
The definition is simple. Giving every student enough use of the language is the work.
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