What are L1 and L2 in Language Learning?

“I’m no good at learning languages”

If you’re reading this blog — and have a pulse — you’ve had that thought before.

Languages take a lot of time, effort, and energy to learn. Every single language learner, from the earliest enthusiast to the hardened hyperpolyglot, has struggled with learning at some point or another. That’s a fact.

However, not a single one of those learners had the same struggles in learning their first language, acquired as children.

These first languages are all acquired effortlessly, naturally, and essentially perfectly. It’s the second, third, and fourth languages (and so on) that give us the trouble.

Why is this?

What makes one learned language different from another?

There are various factors, all of which are tied to the circumstances under which a given language is learned.

Languages learned under different circumstances have been given a variety of names:

First language, mother tongue, native tongue, native language, L1, second language, non-native language, foreign language, L2, third language, L3, L4, L5, among others.

Knowing how to use these terms will help you communicate the differences between each language you know. To keep everything neat and organized, we’ll divide all terms among three classes of languages: L1, L2, and L3.

L1 or First Language

What Does L1 mean?

An L1 is your first language, your native language, or your mother tongue.

You are a native speaker of that language.

Every developmentally healthy human being has a first language. Often (but not always) this is the language that was learned during childhood—before puberty—and is the language that is most used and most comfortable for a given person.

First languages are generally maintained for life, with little overt effort on the part of the speaker. This is because first languages are often woven into the personal and sociocultural identities of the native speaker, and he or she uses the language to think and to interact with family and other members of their cultural or ethnic group.

How Are L1s Learned?

L1s are learned through a process known as first language acquisition, or FLA.

This is a complex biological process which is still not yet entirely understood by the scientific community.

Though the intricacies of first language acquisition are beyond the scope of this article, the most commonly agreed-upon aspects of FLA are as follows:

  • First Language Acquisition is the process of gaining the capacity to use human language, where previously no such capacities existed.
  • L1s are acquired automatically, without conscious effort.
  • L1s are learned before puberty, typically during infancy.
  • An acquired L1 is known at native proficiency. According to J. Joseph Lee’s Article The Native Speaker, An Achievable Model?, published in the Asian EFL journal, native speaker have proficiency represented by an “internalized knowledge” of several areas of language, including:
    • Appropriate use of idiomatic expressions
    • Correctness of language form
    • Natural pronunciation
    • Cultural context including “response cries”, swear words, and interjections
    • Above average sized vocabulary, collocations and other phraseological items
    • Metaphors
    • Frozen syntax, such as binomials or bi-verbials
    • Nonverbal cultural features

Despite the fact that one’s “native language” are referred to as his or her “first language”, it is possible to have several “first languages”, so long as they are learned prior to puberty. For example, children who grow up in households where two languages are spoken (typically in the case of parents of different linguistic backgrounds) may acquire each of those languages natively. These people are referred to as bilingual.

L2 or Second Language

What Does L2 mean?

An L2 is a second language, a foreign language, a target language, or a foreign tongue.

If you have an L2, you are a non-native speaker of that language.

Unlike L1s, not everyone has an L2. If you have learned or are learning a new language, that language is your L2.

How Are L2s Learned?

L2s are learned through a process known as second language acquisition, or SLA.

Like first language acquisition, second language acquisition is a complex field of linguistics. Though many of its theories and facets are constantly under debate, the general commonalities of SLA are:

  • Second language acquisition is the process of acquiring language capacity after another language (or languages) have already been learned natively.
  • Learning an L2 requires conscious effort.
  • L2s are not learned during infancy, and most often after puberty.
  • Theoretically, an acquired L2 can only be known at non-native proficiencies. Exactly how proficient a language learner can become in a second language can range widely, but the general scientific consensus is that an L2 cannot be mastered to the same level as an L1. Highly advanced L2 learners are often called near-native speakers.
  • Though capacity in both L1s and L2s can deteriorate from lack of use (through a process called attrition), L2 capacity is considered to decrease faster from misuse than their L1 counterparts.

As with the term L1 above, the use of the number two in “L2” or “second language” does not necessarily refer to the exact numerical order in which a language is acquired, but only that the language was learned non-natively. In nearly all cases, L2 can be used to refer to any number of languages learned after puberty. 

Together, L1 and L2 are the major language categories by acquisition. In the large majority of situations, L1 will refer to native languages, while L2 will refer to non-native or target languages, regardless of the numbers of each.

L3 or Third Language

What Does L3 Mean?

An L3 is a third language, or a second foreign or non-native language.

According to researcher Jasone Cenoz, a third language is “a language that is different from the first and the second and is acquired after them.” (Cenoz 2013, p. 3)

Considering a given L3 only has to be different from an L1 and the first chronologically learned L2, any L3 can also be referred to as Ln, with n representing the numerical order in which that language is acquired (i.e. L4, L5, L6, etc.)

Note that terms like L3, L4, L5, and beyond are rarely used, as these languages are most often referred to as additional L2s.

How Are L3s Learned?

L3s are learned through a process known as Third Language Acquisition, or TLA.

TLA is a young field of research that can be considered a subdomain of SLA. The field itself aims to examine the differences between acquiring a first foreign language and any subsequent foreign languages thereafter.

TLA researcher Jason Cenoz differentiates third language acquisition from second language acquisition in the following way:

“TLA shares many of the characteristics of SLA, but there are also important differences because third language learners already have at least two languages in their linguistic repertoire. Third language learners can use this broader linguistic repertoire when learning a third language. For example, they can relate new structures, new vocabulary or new ways of expressing communicative functions to the two languages they already know, not just to one of them, as in the case of monolinguals.” (Cenoz 2013, p. 4)

According to TLA research, the knowledge of an L3 has a positive effect on the acquisition of an L2 “in most cases”, for many of the reasons cited above (Cenoz 2013, p.9)


No two languages are learned in exactly the same way. The way you learned your first language is fundamentally different from the way you learn any additional language after that. Furthermore, each new language after your first non-native language adds a different reference point within your linguistic repertoire, benefiting and bolstering the acquisition of future languages.

No matter how far you go in your language learning, keep in mind that if you’re reading this article, you’re good enough at language learning to already have a perfectly-acquired L1 under your belt. That means that, with a bit of effort, you have everything it takes to acquire an L2, an L3, and so on. The exact number is up to you.

You just need to make it happen.