What Is Interlanguage?

Definition of Interlanguage

Interlanguage is the linguistic system that second language learners develop while learning a new language. It contains elements from the learner’s first language, elements from the target language, and patterns created by the learner during the learning process.

The term is strongly associated with Larry Selinker, who introduced it in his 1972 article Interlanguage. Selinker argued that learners do not simply produce incorrect versions of the target language. Instead, they develop an independent system that can be studied in its own right.

Simple definition: Interlanguage is the learner’s temporary language system during second language development.

L1

First Language

The learner’s existing language system, which can influence grammar, pronunciation, vocabulary, and word order.

IL

Interlanguage

The learner’s developing system, shaped by transfer, input, practice, feedback, and learning strategies.

L2

Target Language

The language system the learner is moving toward, such as English, Spanish, German, Arabic, or Japanese.

Why Interlanguage Matters

Interlanguage is important because it changes how we understand learner errors. In older approaches, errors were often seen only as failures. Interlanguage theory treats errors as evidence of development. A learner’s mistake can show what rule they are using, what pattern they have noticed, and what stage of development they are in.

This makes interlanguage useful for teachers, learners, linguists, curriculum designers, and language assessment. It helps explain why learners from different language backgrounds make different errors, why some errors disappear naturally, and why some errors become persistent.

Old View of Errors	Interlanguage View
Errors are simply wrong forms.	Errors can reveal the learner’s developing rules.
The learner is failing to copy the target language.	The learner is building a temporary language system.
All mistakes should be corrected immediately.	Some errors need correction, while others may reflect natural developmental stages.
Errors are always caused by the first language.	Errors may come from first language transfer, overgeneralization, instruction, communication strategies, or incomplete acquisition.

Historical Background

Interlanguage became a major concept in second language acquisition in the 1970s. Selinker’s 1972 article helped shift attention from simply comparing learner errors with native-speaker norms to studying learner language as a system. This was a major development in second language acquisition research.

Before interlanguage theory, many learner errors were explained mainly through contrastive analysis, which predicted errors by comparing the learner’s first language and the target language. Contrastive analysis was useful, but incomplete. It could explain some transfer errors, but not errors caused by overgeneralization, learning strategies, or developmental stages.

Before 1970s

Contrastive analysis

Researchers often focused on how differences between the first language and target language caused learner errors.

1972

Selinker’s interlanguage

Learner language was described as a developing system with its own internal structure.

Later SLA research

Developmental systems

Researchers studied variation, fossilization, feedback, input, output, noticing, and learner strategies.

Main Features of Interlanguage

Interlanguage has several important features. It is systematic, changeable, influenced by multiple sources, and sometimes unstable. It can develop toward the target language, but it can also slow down or fossilize.

Systematic

Learner language follows patterns. Even when learners make errors, those errors often reflect internal rules.

Dynamic

Interlanguage changes as learners receive input, practice, notice gaps, and restructure their knowledge.

Variable

Learners may use the correct form in one situation and an incorrect form in another, especially under pressure.

Permeable

Interlanguage can be influenced by new input, correction, instruction, first language transfer, and target-language exposure.

Developmental

Learners move through stages. Some structures appear only after earlier forms have been acquired.

Prone to Fossilization

Some forms may become stable and resistant to correction, especially if they do not prevent communication.

Interlanguage vs. First Language and Target Language

Interlanguage sits between the first language and the target language, but it is not a simple mixture of the two. It may contain first-language influence, target-language forms, and learner-created rules that do not exist in either language.

Feature	First Language	Interlanguage	Target Language
Stability	Usually stable and fully developed	Developing and changing	The model the learner is moving toward
Rules	Native or dominant language rules	Learner-created rules	Target-language rules
Errors	Usually not described as learner errors	Errors reveal development	Used as the comparison standard
Example	The learner’s original grammar system	She go, I am agree, he married with her	She goes, I agree, he married her

Key point: Interlanguage is not random broken language. It is a developing system with patterns that can be described and improved.

Sources of Interlanguage Forms

Interlanguage forms can come from several sources. Some are influenced by the first language, while others come from the learner’s attempt to simplify, generalize, communicate, or apply classroom instruction.

First Language Transfer

First language transfer happens when learners apply patterns from their first language to the second language. This can affect pronunciation, word order, grammar, vocabulary, collocations, and politeness.

Example: A learner whose first language does not use articles may say I bought book instead of I bought a book.

Overgeneralization

Overgeneralization happens when learners apply a target-language rule too broadly. This shows that the learner has learned a rule, but not yet learned its limits.

Example: A learner may say goed instead of went because they have learned that English regular past tense often uses -ed.

Transfer of Training

Transfer of training occurs when teaching materials or classroom routines influence learner production. If instruction overemphasizes one pattern, learners may use it in too many contexts.

Example: If learners repeatedly practice Do you like…?, they may overuse do in structures where it is not needed.

Communication Strategies

Learners often use strategies to communicate when they do not yet know the exact target form. They may simplify, paraphrase, borrow, gesture, or use approximate words.

Example: A learner who does not know pharmacist may say medicine seller. This is not target-like, but it is communicatively useful.

Common Interlanguage Examples

Interlanguage errors vary by learner background, language pair, proficiency level, exposure, and instruction. The examples below show common patterns, but they should not be treated as fixed predictions for all learners.

Area	Interlanguage Form	Target Form	Possible Explanation
Verb agreement	She go to work every day.	She goes to work every day.	The learner has not fully acquired third-person singular -s.
Articles	I bought book yesterday.	I bought a book yesterday.	The learner may come from a language without articles.
Irregular verbs	He goed home.	He went home.	The learner overgeneralizes regular past tense -ed.
Prepositions	We discussed about the problem.	We discussed the problem.	The learner transfers a preposition pattern from another language.
Collocation	I made a photo.	I took a photo.	The learner translates a natural collocation from the first language.
Pronunciation	Rice and lice sound the same.	/r/ and /l/ are distinguished in English.	The learner’s first language may not contain the same sound contrast.
Pragmatics	Give me your report.	Could you send me your report?	The learner may not yet control indirect requests in English.

Important: Interlanguage examples should be used to understand learning patterns, not to stereotype speakers of particular languages.

Developmental Stages of Interlanguage

Interlanguage changes over time. Learners may begin with simple formulas, then develop rules, then refine those rules through input, feedback, and practice. The stages below are simplified, but they show how learner language can develop.

1

Formulaic Stage

Learners rely on memorized phrases such as How are you?, I don’t know, or My name is….

2

Emerging Rules

Learners begin forming their own sentences and may overgeneralize rules, such as goed or childs.

3

Systematic Development

Learners use more stable patterns and can sometimes explain their choices, but errors remain.

4

Restructuring

Learners revise their internal grammar when they notice gaps between their output and target-language input.

5

Stabilization

Some forms become accurate and automatic, while others may become fossilized if not corrected or noticed.

Interlanguage and Error Analysis

Error analysis is the study of learner errors in order to understand the learner’s developing system. Interlanguage theory made error analysis more meaningful because errors were no longer treated only as failures. They became evidence of internal learning processes.

A teacher analyzing interlanguage asks questions such as:

Is the error caused by first language transfer?

Is the learner overgeneralizing a target-language rule?

Does the learner make this error consistently or only under pressure?

Does the learner understand the rule but fail to use it automatically?

Is the error blocking communication or only affecting accuracy?

Is the learner ready to acquire the target structure?

Error Type	Example	What It May Reveal
Omission	She very happy.	The learner omits the verb is.
Addition	We discussed about the topic.	The learner adds a preposition where English does not require one.
Overgeneralization	I goed to school.	The learner applies regular past tense too broadly.
Misordering	I don’t know where is he.	The learner transfers question word order into an embedded clause.
Approximation	He is a cooker.	The learner creates a logical but non-target word for cook or chef.

Interlanguage and Fossilization

Fossilization happens when parts of a learner’s interlanguage become stable and resistant to change. A learner may communicate fluently but continue to use certain non-target forms for years.

Fossilization can affect pronunciation, grammar, word choice, collocations, and pragmatics. It often occurs when a form does not prevent communication, when feedback is limited, or when the learner has little motivation to improve accuracy beyond functional communication.

Possible Fossilized Area	Example	Why It Persists
Pronunciation	Persistent difficulty distinguishing /ɪ/ and /iː/ in ship and sheep.	The learner may not hear or produce the sound contrast accurately.
Grammar	Regular omission of third-person -s.	The error rarely blocks communication, so it may go uncorrected.
Collocation	Make a party instead of have a party or throw a party.	Direct translation may feel natural to the learner.
Pragmatics	Overly direct requests in formal English.	The learner may not notice the social meaning of indirectness.

Learning point: Fossilization does not mean improvement is impossible. It means the learner needs focused noticing, feedback, and repeated practice to change an automatic pattern.

Interlanguage and Variability

Interlanguage is often variable. A learner may produce the correct form in a grammar exercise but make an error during spontaneous conversation. This does not mean the learner has forgotten the rule. It may mean the rule is not yet automatic.

Variability can depend on attention, task difficulty, planning time, audience, anxiety, speed, topic, and formality. Learners usually perform better when they have time to plan and monitor their language.

Controlled Practice

She goes to work every day.

The learner has time to focus on grammar.

Spontaneous Speech

She go to work every day.

The learner focuses on meaning and speaks quickly.

Teaching implication: Accuracy in drills does not always mean accuracy in communication. Learners need guided practice and real output.

Interlanguage and the Noticing Hypothesis

The Noticing Hypothesis, associated with Richard Schmidt, argues that learners need to notice language features in input in order to acquire them. In interlanguage development, noticing helps learners compare their own output with target-language forms.

For example, a learner may repeatedly say I am agree. If they hear many examples of I agree but never notice the difference, the interlanguage form may continue. Once the learner notices the gap, correction becomes more possible.

1

Learner produces an interlanguage form.

2

Learner hears or reads the target form.

3

Learner notices a gap.

4

Learner practices the target form.

5

The interlanguage system restructures.

Interlanguage in Pronunciation

Interlanguage is not only about grammar. Pronunciation also develops through interlanguage. Learners may use sounds, rhythm, stress, and intonation patterns from their first language while developing target-language pronunciation.

Pronunciation Area	Interlanguage Pattern	Target Development
Sound contrast	A learner pronounces ship and sheep similarly.	The learner learns to hear and produce /ɪ/ and /iː/ separately.
Consonant clusters	A learner adds a vowel in school, producing something like eschool.	The learner practices English initial consonant clusters.
Word stress	A learner stresses the wrong syllable in photography.	The learner acquires stress patterns across word families.
Intonation	A learner uses first-language pitch patterns in English questions.	The learner practices target-language intonation for questions, statements, and politeness.

Interlanguage in Vocabulary and Collocations

Learners also build an interlanguage lexicon. This means they may know many target-language words but not yet use them with fully natural meanings, collocations, register, or grammar patterns.

Interlanguage Form	Target Form	Issue
make a mistake	make a mistake	Correct collocation.
do a mistake	make a mistake	Wrong verb choice, often from transfer or overgeneralization.
strong rain	heavy rain	Collocation problem.
big problem	big problem or serious problem	May be correct, but register and nuance depend on context.
economic	economic or economical	Learner must distinguish related adjectives with different meanings.

Vocabulary tip: Interlanguage vocabulary improves faster when learners study words in phrases and sentences, not only as isolated translations.

Interlanguage and Pragmatics

Pragmatics is the study of how language is used in social contexts. Interlanguage pragmatics looks at how learners develop the ability to make requests, apologize, disagree, refuse, compliment, show politeness, and manage conversation in the target language.

A learner may know correct grammar but still sound too direct, too formal, too informal, or socially unnatural. This is not only a vocabulary issue. It is part of developing communicative competence.

Situation	Possible Interlanguage Form	More Natural Target Form
Requesting help from a teacher	Explain this to me.	Could you explain this to me?
Disagreeing in a meeting	You are wrong.	I see your point, but I think there may be another way to look at it.
Refusing an invitation	No, I cannot come.	Thanks for inviting me, but I’m afraid I can’t make it.
Making a professional request	Send me the file today.	Could you send me the file today when you have a chance?

How Teachers Can Use Interlanguage

Teachers can use interlanguage analysis to understand what learners are ready to learn, which errors are most important, and how to design useful practice. Not every error needs the same kind of correction.

Identify Patterns

Look for repeated errors instead of isolated mistakes. Repeated patterns reveal the learner’s internal system.

Target High-Impact Errors

Focus on errors that block communication, affect academic or professional accuracy, or appear repeatedly.

Balance Fluency and Accuracy

Give learners time for free communication and time for careful correction.

Use Feedback Strategically

Use recasts, clarification requests, direct correction, metalinguistic feedback, and guided self-correction.

Create Noticing Tasks

Help learners compare their own output with target examples.

Track Development

Keep samples of learner writing or speech to observe changes over time.

How Learners Can Improve Their Interlanguage

Learners can improve their interlanguage by noticing errors, getting feedback, using authentic input, practicing output, and reviewing repeated mistakes. The goal is not to eliminate every trace of learner language immediately. The goal is gradual restructuring.

1

Record Yourself

Record short speaking tasks and listen for repeated pronunciation, grammar, or fluency patterns.

2

Keep an Error Log

Write down repeated errors and group them by grammar, vocabulary, pronunciation, or pragmatics.

3

Compare with Native Input

Read and listen to authentic examples, then compare them with your own sentences.

4

Practice One Pattern

Focus on one repeated error at a time, such as articles, prepositions, word stress, or indirect requests.

5

Use Corrected Forms in Communication

Move from drills to real speaking and writing so the corrected pattern becomes automatic.

Interlanguage is related to several other terms in language learning and linguistics, but it is not identical to them.

Term	Meaning	Difference from Interlanguage
Learner language	The language produced by a learner.	Often used more broadly. Interlanguage emphasizes the internal system behind learner production.
Error analysis	The study of learner errors.	Error analysis is a method. Interlanguage is the developing system being studied.
Fossilization	Stabilization of non-target forms.	Fossilization is one possible outcome within interlanguage development.
Transfer	Influence from a known language.	Transfer is one source of interlanguage forms.
Pidgin	A simplified contact language used between groups without a shared language.	Interlanguage is individual learner language, not a community contact language.
Accent	Pronunciation features of a speaker or group.	Accent may be part of interlanguage, but interlanguage also includes grammar, vocabulary, and pragmatics.

Limitations of Interlanguage Theory

Interlanguage theory is useful, but it does not explain everything about second language learning. Learners are not only internal grammar systems. They are social people using language in real situations. Motivation, identity, community, classroom context, technology, and social power also shape language learning.

Limitation	Explanation
Focus on errors	Interlanguage analysis can overemphasize errors if teachers ignore communicative success.
Native-speaker target	Some models assume a native-speaker standard, but many learners use languages for international communication.
Social context	Interlanguage theory may not fully explain identity, power, motivation, and interactional context.
Individual variation	Learners differ in goals, exposure, age, memory, anxiety, learning style, and motivation.

Balanced view: Interlanguage is a powerful concept, but it should be combined with research on interaction, sociolinguistics, classroom learning, and learner identity.

Practical Examples for English Learners

English learners often show interlanguage patterns in areas where English differs strongly from their first language. The examples below show how a teacher or learner can analyze the problem and choose a practice strategy.

Interlanguage Pattern	Target Pattern	Practice Strategy
I am agree.	I agree.	Practice stative verb patterns: I agree, I know, I understand.
She has 25 years.	She is 25 years old.	Practice age expressions in full sentences.
It depends of the situation.	It depends on the situation.	Learn verbs with their common prepositions.
I am here since Monday.	I have been here since Monday.	Practice present perfect with since and for.
I very like this movie.	I really like this movie.	Practice adverb position before verbs and adjectives.
Can you borrow me your pen?	Can you lend me your pen?	Contrast borrow and lend in role-play.

FAQ

What is interlanguage in simple words?

Interlanguage is the temporary language system a learner creates while learning a second language. It contains features of the first language, the target language, and the learner’s own developing rules.

Who introduced the term interlanguage?

The term interlanguage is strongly associated with Larry Selinker, who introduced it in his 1972 article Interlanguage.

Is interlanguage the same as making mistakes?

No. Mistakes are only part of interlanguage. Interlanguage is the whole developing system behind a learner’s second language production, including correct forms, errors, strategies, and patterns.

Why do learners create interlanguage?

Learners create interlanguage because they are actively building a new language system. They use first-language knowledge, target-language input, learning strategies, communication strategies, and generalization.

Can interlanguage become fossilized?

Yes. Some interlanguage forms can become fossilized, meaning they become stable and resistant to correction. This is common when errors do not prevent communication or when feedback is limited.

How can learners improve their interlanguage?

Learners can improve their interlanguage through noticing, feedback, authentic input, guided output, focused practice, recording themselves, and tracking repeated errors.