French Liaison Rules: When to Link Words (and Not To)

If you can read French but still can’t follow it spoken aloud, liaison is almost certainly why. You read les amis as two tidy chunks, then a French speaker says lay-zah-mee and the word boundaries vanish. That silent letter you learned to ignore didn’t disappear — it woke up and jumped onto the next word. Once you understand when that happens, spoken French stops sounding like a blur and starts sounding like words again.

The good news is that liaison is rule-governed. There’s a clean three-way split — obligatory, forbidden, and optional — and one heuristic that resolves most cases: only link words that belong together grammatically. Let’s make it click.

What liaison actually is

Liaison means a final consonant that is silent on its own gets pronounced when the next word begins with a vowel sound, attaching to that next word. Take les-style determiners: on its own, les is just /le/ — the s is silent. But in les amis, the s resurfaces as a /z/ and glues onto the front of amis: lay-za-mee.

Two things make it liaison:

1. The consonant is silent in isolation and only appears before a vowel.
2. It happens only between words that are grammatically linked and spoken in the same rhythmic group.

Don’t confuse liaison with enchaînement. In enchaînement the consonant is already pronounced and simply slides to the next syllable: in par intérêt, the r in très-type words and par was always sounded. Liaison only involves a consonant that was silent until a vowel woke it up. Liaison is the dramatic one; enchaînement is automatic and you never have to think about it.

The sound shifts: s/x → z, d → t, f → v

Here’s the detail most guides bury: a liaison consonant often changes its sound. Getting these wrong is what makes a learner sound off even when they link in the right place.

French	English	Liaison sound
les enfants	the children	-s → z
deux euros	two euros	-x → z
un grand ami	a great friend	-d → t
neuf heures	nine o'clock	-f → v
mon oncle	my uncle	-n → nasal n

The big two to memorize: a liaison -s or -x becomes /z/, never an s — so ami in les amis gives lay-za-mee. And a liaison -d hardens to /t/: grand in un grand ami sounds like “gran-tami.” The -f → v shift is essentially limited to two phrases, neuf ans and neuf heures; everywhere else neuf keeps its /f/.

Obligatory liaisons — always link

These are non-negotiable. Skipping them sounds like a mistake. Notice they’re all grammatically bound pairs:

French	English	Why
les enfants	the children	determiner + noun
deux heures	two o'clock	number + noun
nous avons	we have	pronoun + verb
un petit avion	a small plane	adjective + noun
très utile	very useful	adverb + adjective
comment allez-vous	how are you	fixed expression

The pattern is: a determiner is bound to its noun, a number to its noun, a subject pronoun to its verb, a prenominal adjective to its noun. All link, every time.

Forbidden liaisons — never link

These break the “grammatically bound” rule, or are blocked by a specific word. Linking here is an error — or worse, hypercorrection that natives notice instantly.

French	English	Why no link
un livre et un stylo	a book and a pen	never after et
les héros	the heroes	aspirated h blocks it
les enfants écoutent	the children listen	noun ≠ following verb
Jean est là	Jean is here	proper noun resists

The single most important rule: et (“and”) never links to the word after it, no matter how it starts. Say un livre et // un stylo with a clean break.

Aspirated h is the other classic trap. héros begins with an h aspiré that blocks liaison, so les héros is lay // éros — not lay-zéros. Get this wrong and les héros (“the heroes”) becomes les zéros (“the zeros”). The liaison literally changes the meaning.

And the master heuristic in action: a noun is not glued to the verb that follows it. Inside les enfants, the determiner links (lay-zen-fant), but enfants → écoutent does not, because the subject noun and its verb sit in different rhythmic groups.

Optional liaisons — your choice

A third bucket is genuinely optional, and it signals formality. Linking these makes you sound careful, literary, or oratorical — think news anchors and speeches. Dropping them is normal, relaxed conversation.

French	English	When to link
il est arrivé	he has arrived	formal only
ils ont oublié	they forgot	formal only
pas encore	not yet	careful speech

The rule of thumb that keeps you safe: obligatory always, forbidden never, optional → lean toward not linking in conversation. A skipped optional liaison is never wrong; a forced one can sound stilted.

A few tricky exceptions

A handful of words misbehave. Six and dix pronounce their final consonant alone (j’en ai six → sees), drop it before a consonant (six livres → si livres), and use the /z/ liaison before a vowel (six oranges → si-zoranges). The number neuf keeps /f/ everywhere except neuf ans and neuf heures, where it shifts to /v/ — handy to know when you study your numbers 1 to 100. And beware pataquès: the hypercorrect habit of inventing liaisons that don’t exist (saying et-zelle after et, or using the wrong consonant). An invented liaison sounds worse than no liaison at all.

Train your ear next

Liaison is really just the flip side of silent letters: the same consonants that go quiet at the end of a word come roaring back before a vowel. The fastest way to lock it in is to pair this with our guide to French silent letters, then tune your mouth with the French R sound so your enchaînement flows too. Start by listening for just the obligatory cases — les amis, nous avons, deux heures — and you’ll be amazed how quickly spoken French snaps into focus. You’ve got this.