Have you ever listened to a French person speak and thought: how on earth do they get from those individual words on the page to that beautiful, smooth, flowing sound that comes out of their mouth?

The answer is liaison. It's the invisible glue of spoken French. It's why les amis sounds like "lay-zah-mee" and not "lay ah-mee." Why vous avez becomes "voo-zah-vay." Why French sometimes feels like one continuous stream of sound rather than separate words.

For learners, liaison is one of the most confusing aspects of French pronunciation. Some final consonants come alive when the next word starts with a vowel. Others don't. Some are mandatory. Some are forbidden. Some are optional. The rules feel arbitrary, the exceptions feel endless, and most teachers either oversimplify or drown you in a list of cases.

So today, I want to walk you through liaison in a way that actually makes sense. We'll cover the three categories (mandatory, optional, forbidden), the patterns you can rely on, and the cases that trip up English speakers most. By the end of this post, you'll be able to listen to French and understand what your ear is hearing, and you'll know when to liaise and when to stop.

If you're not sure exactly what level you're at right now, you can take my free placement test here before we dive in.

What liaison actually is

Liaison happens when the final consonant of a word — which is normally silent in French — gets pronounced because the next word starts with a vowel sound.

A clean example: the word vous. Said alone, the final "s" is silent. You say "voo." But in vous avez, the "s" comes alive and connects to the "a" of avez, so the whole thing sounds like "voo-zah-vay."

Three things to notice about this:

First, liaison only happens when the next word starts with a vowel sound (or a silent "h"). If the next word starts with a consonant, the final consonant of the previous word stays silent. Vous parlez is just "voo par-lay." No liaison, because parlez starts with a "p."

Second, the consonant that comes alive often changes its sound slightly. The "s" in vous becomes a "z" sound when it liaises. The "d" in grand becomes a "t" sound. The "f" in neuf (when it means "nine") sometimes becomes a "v." More on these shifts in a minute.

Third, liaison is part of the rhythm of French. It's not optional in the sense of "you can skip it if you want." Some liaisons are mandatory, and skipping them makes you sound foreign or robotic. Other liaisons are forbidden, and forcing them makes you sound foreign in a different way. Getting this right is one of the things that quietly separates fluent-sounding French from textbook French.

The three categories: mandatory, optional, forbidden

Every potential liaison in French falls into one of three buckets.

Mandatory liaisons must happen. Skipping them makes the sentence sound wrong.

Optional liaisons can happen or not. Whether they happen depends on register (formal vs casual) and personal habit.

Forbidden liaisons must not happen. Forcing them sounds wrong, sometimes even ridiculous.

Let me walk you through each.

Mandatory liaisons

These happen automatically. If you skip them, native speakers will notice immediately that your French sounds off.

1. Between articles and nouns, or pronouns and verbs

This is the most common mandatory liaison. Whenever a small grammatical word is followed by a word starting with a vowel, you liaise.

• Les amis — "lay-zah-mee" (the friends)
• Un ami — "un-nah-mee" (a friend)
• Mon ami — "mon-nah-mee" (my friend)
• Vous avez — "voo-zah-vay" (you have)
• Ils ont — "eel-zon" (they have)
• Nous étions — "noo-zay-tee-on" (we were)

Notice how the final consonant of the small word jumps over and attaches to the vowel of the next word. This is the rhythm of French.

2. After short common adjectives that come before a noun

When an adjective sits before a noun and ends in a normally-silent consonant, you liaise.

• Un grand homme — "un gran-tomm" (a great man) — note that the "d" sounds like "t"
• Un petit ami — "un peu-tee-tah-mee" (a boyfriend)
• Les bons amis — "lay bon-zah-mee" (the good friends)
• Un ancien élève — "un an-syen-nay-lev" (a former student)

This is one of the trickier cases for learners because you have to know which adjectives go before the noun, and you have to remember the consonant shift (d → t, s → z, f → v).

3. After certain prepositions and conjunctions

Short, common prepositions almost always trigger liaison.

• Chez elle — "shay-zell" (at her place)
• Sans aide — "san-zed" (without help)
• Dans une maison — "dan-zoon may-zon" (in a house)
• En avion — "an-nah-vee-on" (by plane)

4. After "est" and certain forms of "être"

This is one of the most missed liaisons by learners. The "t" of est connects to the next word.

• C'est important — "say-tan-por-tan" (it's important)
• Il est ici — "ee-lay-tee-see" (he's here)
• Elle est arrivée — "ell-ay-tah-ree-vay" (she has arrived)

Skipping this liaison is one of the surest signs of a non-native speaker. If you fix only one thing about your liaison habits, fix this one.

Optional liaisons

These are where personal style and register come in. Some speakers liaise more, some less. Formal speech (a news anchor, a politician giving a speech, a poetry reading) tends to use more liaisons. Casual speech uses fewer.

A few classic optional liaisons:

• After verb forms in passé composé: je suis allée can be "zhuh swee zah-lay" or "zhuh swee ah-lay." Both are correct.
• After the conjunction mais: mais aussi can be "may-zo-see" (more formal) or "may o-see" (more casual).
• After toujours, beaucoup, depuis, etc. before a verb: beaucoup aimé might be "boo-koo-pay-may" (formal) or "boo-koo ay-may" (casual).

The rule of thumb: when in doubt, follow what you hear. Listen to the kind of French you want to sound like (your favorite podcast host, the actors in shows you love, French friends you have) and copy their habits. There's no single right answer, only registers.

Forbidden liaisons

These are the cases where forcing a liaison sounds wrong. Sometimes it sounds slightly off. Sometimes it sounds like a serious error. Sometimes it sounds funny.

1. After a singular noun

This is the big one. You don't liaise after a singular noun, even if the next word starts with a vowel.

• Un étudiant intelligent — "un ay-too-dee-yan an-tay-lee-zhan" (NOT "un ay-too-dee-yan-tan-tay-lee-zhan")
• Un garçon attentif — "un gar-son ah-tan-teef" (NOT "un gar-son-nah-tan-teef")

The plural is different. In les étudiants intelligents, you liaise twice (les-zay-too-dee-yan-zan-tay-lee-zhan). But after a singular noun, no liaison.

2. Before "h aspiré"

Some words in French start with what's called an h aspiré (aspirated h), which behaves like a consonant even though it's silent. With these words, no liaison.

• Les héros — "lay ay-roh" (NOT "lay-zay-roh")
• Les haricots — "lay ah-ree-koh" (NOT "lay-zah-ree-koh") — this one is famous for tripping up even native speakers in formal contexts
• En haut — "an oh" (NOT "an-noh")

Unfortunately, there's no rule for which "h" words are aspirated and which aren't. You have to learn them individually. The good news: there are only about a hundred common ones, and dictionaries mark them with a small symbol.

3. After "et" (and)

This is a famous one. You never liaise after et. Ever.

• Il et elle — "eel ay ell" (NOT "eel-tay ell" or "eel-zay ell")
• Mon père et un ami — "mon pair ay un-nah-mee" (NOT "mon pair-tay un-nah-mee")

The conjunction et is treated as if it ends in a vowel for liaison purposes, even though it technically ends in a "t."

4. Before numbers in certain contexts

Numbers create complications. Generally, you don't liaise before un, huit, or onze in counting contexts.

• Les onze enfants — "lay onz an-fan" (NOT "lay-zonz an-fan")
• Les huit jours — "lay weet zhoor" (NOT "lay-zweet zhoor")

This rule has many exceptions and personal variations, so don't stress about it too much. Listen and copy what you hear.

The consonant shifts to remember

When liaisons happen, certain consonants change their sound. This catches learners off guard because the spelling doesn't match what comes out of the mouth.

• S becomes Z: les amis sounds like "lay-zah-mee"
• X becomes Z: deux amis sounds like "duh-zah-mee"
• D becomes T: un grand homme sounds like "un gran-tomm"
• F sometimes becomes V: in neuf ans, sounds like "nuh-van" (but not in all contexts)
• G sometimes becomes K: rare in modern French, but sang impur in the Marseillaise sounds like "san-kan-poor"

The most common ones are S → Z and D → T. If you internalize just those two, you'll handle the vast majority of liaisons correctly.

How to actually train your liaison

Reading rules won't make liaisons automatic. Your mouth has to physically learn to do them. Here's what works.

Shadow native speakers. Pick a clip of a French speaker (a podcast, an interview, a movie scene) and repeat after them, copying not just the words but the exact way they connect them. Pay attention to where their words run together. Mimic that exactly.

Read out loud. Take a French paragraph and read it aloud, deliberately marking the liaisons in your head as you go. The more you do this, the more automatic the connections become.

Listen for the rhythm, not the words. When you listen to French, try to hear it as a flow rather than as separate words. The flow is created by liaisons (and elisions, like l'ami instead of le ami). Once you tune your ear to the flow, your own French will start to flow too.

If you want more strategies for sounding more natural, my post on the 100 most common spoken French phrases you'll hear everywhere is a good companion. And if your French has been sounding a bit stiff, my post on why you're stuck at intermediate French (and how to fix it) addresses some of the underlying causes.

Don't aim for perfection

One last thing, because it matters. You don't have to get every liaison right to sound great in French.

Native French speakers get optional liaisons "wrong" all the time, in different directions. Some are very liaison-heavy, others are very casual. The exact rules of forbidden liaisons get violated occasionally even by educated speakers. Les haricots is famously mispronounced les zaricots by lots of French people in casual speech, and the world keeps turning.

What matters is getting the mandatory ones right (especially after les, des, vous, est, and similar small grammatical words) and avoiding the most common forbidden ones (after singular nouns, before aspirated h, after et). If you nail those, your French will sound noticeably more fluent.

Pick one mandatory liaison case from this post and practice it deliberately this week. Maybe it's vous avez. Maybe it's c'est important. Maybe it's les amis. Just one. Use it out loud, in real sentences, until it feels automatic.

Then move on to the next one.

If you want a structured way to learn French — including pronunciation, rhythm, and the kind of sound work that makes liaisons natural — you can try a free sample lesson from my course here and see how I teach.

À très vite, Clémence