French Liaison Rules: When You Must, Can't, and May
French liaison isn't always optional - some are mandatory, some are forbidden. The full rule set: pronoun+verb, article+noun, and the never-liaise cases.
French liaison has three tiers: mandatory (pronoun+verb, article+noun, number+noun - nous avons, les amis, deux heures), forbidden (never after et, never before an aspirated h like les / haricots), and optional/stylistic, used more in formal speech than casual conversation.
Quick answer
French liaison has three tiers: mandatory (pronoun+verb, article+noun, number+noun - nous avons, les amis, deux heures), forbidden (never after et, never before an aspirated h like les / haricots), and optional/stylistic, used more in formal speech than casual conversation.
Master liaison with real audio examples. Get it on the App Store or Google Play.
This is the deep-dive companion to the liaison section in the French pronunciation guide.
Mandatory liaisons
| Pattern | Example |
|---|---|
| pronoun + verb | nous avons |
| article/adjective + noun | les amis, un grand homme |
| number + noun | deux heures |
Forbidden liaisons
Never after et - see why et never takes liaison. Never before an aspirated h: les / haricots (no liaison), compared with les hommes which DOES liaise, since that h is silent/mute rather than aspirated. Liaison is also blocked after most singular nouns.
Optional/stylistic liaisons
Formal speech - speeches, news broadcasts - makes more liaisons than casual conversation does. The same sentence can sound noticeably more “liaised” in a formal register than in everyday chat, without either being wrong.
Sound-change reminders
In liaison, s/x become /z/ (les amis, deux heures), and d becomes /t/ (un grand homme). For the related topic of when letters vanish entirely, see silent letters in French.
Liaison that sounds natural
LexiFr teaches liaison with native audio examples across all three tiers.
Free to start - no ads, no streak guilt. Your first 200 words are waiting.
Questions about this note
When is liaison mandatory in French?
Between a pronoun and verb, an article/adjective and noun, or a number and noun.
When is liaison forbidden?
After et, and before an aspirated h (les / haricots).
What's an aspirated h?
A silent h that still blocks liaison and elision, unlike a "mute" h.
Does liaison change the sound of s or x?
Yes - both become /z/ in liaison: les amis.
Is liaison used the same way in casual and formal speech?
No - formal/careful speech adds more optional liaisons than casual conversation.