Optional Liaison | French Grammar

If obligatory liaison is the rule you cannot bend and forbidden liaison is the line you cannot cross, optional liaison is everything in between — a wide gray zone where French speakers choose, consciously or not, whether to make the link based on register, formality, and personal style. The same sentence can be spoken with three liaisons in a TV news broadcast and zero in a casual phone call to a friend, and both versions are perfectly correct French.

This page maps the territory of optional liaisons, shows you how the dial works, and helps you calibrate your own choices to the situation you are in. The goal is not to memorize a list but to understand the gradient.

The register dial

Optional liaisons function as a sociolinguistic dial. Turn the dial up — make every possible liaison — and your speech sounds formal, literary, or oratorical. Turn the dial down — make only the obligatory ones — and your speech sounds casual, familiar, or even rough. Most spoken French sits somewhere in the middle.

Register	What you'll hear	Where
Highly formal / oratorical	Almost all optional liaisons made	Speeches, poetry recitation, classical theatre, formal lectures
Careful / journalistic	Many optional liaisons made	News broadcasts, formal interviews, prepared talks
Neutral / standard	Some optional liaisons made	Everyday educated conversation, business meetings
Casual / familiar	Few optional liaisons made	Conversation among friends, family, informal radio
Colloquial / popular	Almost no optional liaisons	Texting voiced aloud, casual youth speech, street register

A practical guideline: err slightly toward more liaison when speaking French as a learner. Native speakers can drop liaisons fluently because their language sounds native to begin with; if a learner skips them, the speech can sound choppy and unconfident. Adding one extra optional liaison rarely sounds bad. Skipping a confidence-building one often does.

Where optional liaisons appear

The most common optional contexts cluster around four types of structure.

Verb + complement

After a finite verb, before its object, complement, or adverb. This is the largest category.

Je suis allé en France l'été dernier.

I went to France last summer.

In careful speech: /ʒə.sɥi.za.le/, with liaison between suis and allé. In casual speech: /ʒə.sɥi.a.le/ or even /ʃɥi.a.le/, no liaison.

Il faut absolument que tu viennes.

You absolutely have to come.

Careful: /fo.tab.so.ly.mɑ̃/ with /t/ liaison from faut. Casual: /fo.ab.so.ly.mɑ̃/ with no liaison.

Nous avons attendu plus d'une heure.

We waited more than an hour.

The link between avons and attendu is technically optional but extremely common — the obligatory auxiliary + past participle rule of obligatory liaison wins out for native speakers in normal speech. Different sources put this in different boxes; treat it as effectively standard.

Verbs like avoir, être, vouloir, pouvoir, devoir, savoir, falloir followed by an infinitive.

Je voudrais aller au cinéma ce soir.

I'd like to go to the cinema tonight.

Careful: /vu.dʁɛ.za.le/. Casual: /vu.dʁɛ.a.le/.

Tu peux essayer, ça ne coûte rien.

You can try, it costs nothing.

Careful: /pø.ze.sɛ.je/. Casual: /pø.e.sɛ.je/.

Il faut être à l'heure.

One must be on time.

Careful: /fo.tɛtʁ/. Casual: /fo.ɛtʁ/.

After plural noun (before adjective)

When a plural noun is followed by an adjective, liaison is optional. In careful speech the plural -s links to the adjective; in casual speech it does not.

Des enfants intelligents jouent dans la cour.

Some intelligent children are playing in the courtyard.

Careful: /ɑ̃.fɑ̃.zɛ̃.te.li.ʒɑ̃/. Casual: /ɑ̃.fɑ̃.ɛ̃.te.li.ʒɑ̃/.

Les soldats américains sont arrivés.

The American soldiers have arrived.

Careful: /sɔl.da.za.me.ʁi.kɛ̃/. Casual: /sɔl.da.a.me.ʁi.kɛ̃/.

This contrasts with singular noun + adjective, where liaison is forbidden entirely (see Forbidden Liaison). The plural -s is what makes the liaison even possible.

After a polysyllabic adverb

Multi-syllable adverbs like beaucoup, vraiment, absolument, toujours, jamais, souvent, longtemps may liaise with a following vowel-initial word.

Il est toujours en retard, ce garçon.

That boy is always late.

Careful: /tu.ʒu.zɑ̃.ʁə.taʁ/ — the silent -s of toujours surfaces as /z/. Casual: /tu.ʒuʁ.ɑ̃.ʁə.taʁ/ — no liaison, just enchaînement of the /ʁ/.

J'ai beaucoup appris cette année.

I learned a lot this year.

Careful: /bo.ku.pa.pʁi/. Casual: /bo.ku.a.pʁi/.

C'est vraiment intéressant, ton idée.

Your idea is really interesting.

Careful: /vʁɛ.mɑ̃.tɛ̃.te.ʁe.sɑ̃/. Casual: no liaison.

After short prepositions like avant, après, devant, depuis

These are intermediate cases. The shorter prepositions on the obligatory list (en, dans, sans, sous, chez) always liaise; the longer or less-frequent ones often do not.

Avant un examen, je révise jusque tard.

Before an exam, I review until late.

Careful: /a.vɑ̃.tɛ̃.nɛɡ.za.mɛ̃/. Casual: no liaison.

Après une heure de marche, on s'est reposés.

After an hour of walking, we rested.

Careful: /a.pʁɛ.zyn/. Casual: /a.pʁɛ.yn/.

Liaisons that are dying out

A few liaisons are in active retreat. They were standard a generation ago but now sound markedly old-fashioned outside formal media. Examples include:

Liaison after most plural verb forms (ils mangent encore → /mɑ̃ʒ.tɑ̃.kɔʁ/ vs /mɑ̃ʒ.ɑ̃.kɔʁ/)
Liaison between pas (negative) and what follows (pas important → /pa.zɛ̃.pɔʁ.tɑ̃/ vs /pa.ɛ̃.pɔʁ.tɑ̃/)
Liaison after monosyllabic adverbs fort, bien, trop (trop important → /tʁo.pɛ̃.pɔʁ.tɑ̃/ vs /tʁo.ɛ̃.pɔʁ.tɑ̃/)

For learners, the safer modern choice is to skip these in conversation but recognize them in older recordings, formal speeches, and song lyrics.

Ce n'est pas important, ne t'inquiète pas.

It's not important, don't worry.

Modern conversational: /pa.ɛ̃.pɔʁ.tɑ̃/. Formal/older: /pa.zɛ̃.pɔʁ.tɑ̃/. Both are heard.

When the optional liaison does fire, the rules don't change

The conversion table for liaison consonants is the same as for obligatory liaisons: written -s/-x/-z → /z/, written -t/-d → /t/, written -n → /n/, written -r → /ʁ/. The difference is only whether to liaise, not how.

Il est arrivé en train ce matin.

He arrived by train this morning.

If you make the optional liaison: /ɛ.ta.ʁi.ve/ — the -t of est surfaces as /t/.

Vous avez un message important.

You have an important message.

If you make the liaison after avez: /a.ve.zɛ̃/ — the -z surfaces as /z/.

Calibrating your own register

Three rules of thumb help you choose:

Match your interlocutor. If the person you're speaking with makes few liaisons, mirror them. If they make many, you can too.
Default to the middle for most situations. Make obligatory liaisons; make the most natural-sounding optional ones (auxiliary + past participle, verb + adverb, common preposition + complement); skip the rest.
Crank the dial up for prepared speech. When giving a presentation, reading aloud, or speaking in a formal setting, lean into the liaisons. They are part of the sound of careful French.

A practical exercise: read the same paragraph three times — once with every possible optional liaison, once with no optional liaisons, and once in your natural register. Listen to all three. The first will sound elevated, the second clipped or hesitant, the third — if you have calibrated correctly — like ordinary educated French.

Comparison with English

English speakers do not have a comparable register dial built into the consonants of their speech. The closest English analogue is contractions: I am going vs I'm going vs I'm gonna. The choice signals register without changing meaning. Optional liaison in French is similar in spirit but operates in the opposite direction: instead of removing sounds for casual speech, French adds sounds for formal speech.

A second analogue is consciously enunciated articulation in formal English: I am going to the office tomorrow morning with crisp /t/ and /d/ stops sounds more formal than the same sentence with reduced /ɾ/ flaps. French speakers reach for liaison where English speakers reach for cleaner articulation.

Common Mistakes

❌ Making every possible liaison in casual conversation

Sounds stilted, hyper-correct, almost theatrical for everyday chat.

✅ Making obligatory liaisons + a few natural optional ones

Sounds like an educated native speaker.

❌ Treating all liaisons as obligatory because you can't tell them apart

Hard to fix later — you internalize the wrong rhythm.

✅ Learning the obligatory list first, then adding optional ones

Builds the right reflexes layer by layer.

❌ pas /z/ encore — pa.zɑ̃.kɔʁ

The pas-liaison is dated outside formal speech.

✅ pas encore — pa.ɑ̃.kɔʁ

Modern colloquial — no liaison after pas.

❌ Skipping the auxiliary-participle liaison even in normal speech

il est /ɛ/ arrivé sounds disconnected.

✅ Linking auxiliary to participle by default

il est arrivé — /ɛ.ta.ʁi.ve/.

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If you are uncertain whether to make a liaison, listen for what people around you actually do. French speakers are sensitive to register and will modulate their own liaisons depending on whom they are with. Match the room, and you will rarely sound off.

Practical drill

Take this sentence and read it three ways:

Nous avons attendu pendant une heure devant un café charmant.

Maximum (formal/oratorical): /nu.za.vɔ̃.za.tɑ̃.dy.pɑ̃.dɑ̃.tyn.œʁ.də.vɑ̃.tɛ̃.ka.fe.ʃaʁ.mɑ̃/

Standard (educated everyday): /nu.za.vɔ̃.za.tɑ̃.dy.pɑ̃.dɑ̃.tyn.œʁ.də.vɑ̃.ɛ̃.ka.fe.ʃaʁ.mɑ̃/

Casual (conversational): /nu.za.vɔ̃.a.tɑ̃.dy.pɑ̃.dɑ̃.yn.œʁ.də.vɑ̃.ɛ̃.ka.fe.ʃaʁ.mɑ̃/

Note that the obligatory liaison nous avons /nu.za.vɔ̃/ (subject pronoun + verb) survives in all three versions. What changes is the optional ones: between avons and attendu (auxiliary + past participle), between pendant and une (preposition + complement), and between devant and un (preposition + complement). The skeleton of the sentence is the same; the texture varies.

Key takeaways

Optional liaisons are a register dial. Making more of them lifts your speech toward formal or oratorical; making fewer lowers it toward casual or familiar. The principal contexts are verb + complement, auxiliary + infinitive, plural noun + adjective, polysyllabic adverb + word, and longer prepositions. The consonant conversions are identical to those of obligatory liaisons (-s/-x/-z → /z/, -t/-d → /t/, -n → /n/). Your job as a learner is not to memorize every case, but to develop a feel for which level you want to project — and to match the people you speak with.

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