When does a French verb use etre instead of avoir in the passe compose?

For two cases. First, a closed set of about fifteen intransitive verbs of movement and state - the MRS VANDERTRAMP mnemonic: aller, venir, arriver, partir, monter, descendre, naitre, mourir, entrer, sortir, retourner, rester, tomber, devenir, passer (and their compounds revenir, repartir, rentrer). Every other intransitive verb takes avoir. Second, all reflexive verbs - se laver, se lever, s'appeler - use etre in compound tenses, regardless of their meaning. When the auxiliary is etre, the past participle agrees with the subject in gender and number, like an adjective.

How do you form the French past participle?

Three regular patterns. -er verbs drop -er and add -e: parler -> parle, manger -> mange. -ir verbs (the choisir / finir cluster) drop -ir and add -i: finir -> fini, choisir -> choisi. -re verbs drop -re and add -u: attendre -> attendu, vendre -> vendu. Three irregulars at Foundation tier: etre -> ete (been), avoir -> eu (had), faire -> fait (done / made). A handful of further irregulars come up constantly: voir -> vu, dire -> dit, prendre -> pris, mettre -> mis, ecrire -> ecrit.

French Passe Compose

The passe compose is the default French past tense. It covers both "I did X" and "I have done X" in English. The shape is always: auxiliary (avoir or etre) + past participle.

J'ai parle. (I spoke / I have spoken.)
Nous avons mange. (We ate / We have eaten.)
Elle est partie. (She left / She has left.)

The two auxiliaries

The main puzzle of the passe compose is which auxiliary the verb takes.

Avoir is the default. Most verbs use it.

Etre is used in two specific cases:

A closed set of about fifteen intransitive verbs of movement or state.
All reflexive verbs (se laver, se lever, s'appeler, etc.).

The etre set: MRS VANDERTRAMP

A mnemonic. Each letter is the start of a verb in the closed set.

Verb	Meaning	Past participle
Mourir	to die	mort
Retourner	to return	retourne
Sortir	to go out	sorti
Venir	to come	venu
Arriver	to arrive	arrive
Naitre	to be born	ne
Descendre	to go down	descendu
Entrer	to enter	entre
Rentrer	to come home	rentre
Tomber	to fall	tombe
Rester	to stay	reste
Aller	to go	alle
Monter	to go up	monte
Partir	to leave	parti
Passer	to pass by	passe

Plus compounds: devenir (to become), revenir (to come back), repartir (to leave again). These are the only verbs that take etre as their everyday auxiliary. Everything else uses avoir.

Reflexives

All reflexive verbs use etre in compound tenses, regardless of meaning.

Je me suis leve. (I got up.)
Elle s'est lavee. (She washed.)
Nous nous sommes couches. (We went to bed.)

The reflexive pronoun stays before the auxiliary. The past participle agrees - see below.

The past participle

Three regular patterns, by verb ending.

Ending	Drop and add	Example
-er	-er + e	parler -> parle
-ir cluster	-ir + i	finir -> fini
-re cluster	-re + u	attendre -> attendu

The three irregulars you must memorise from day one:

Verb	Past participle	Meaning
etre	ete	been
avoir	eu	had
faire	fait	done / made

Other common irregulars that come up in the first month: voir -> vu, dire -> dit, prendre -> pris, mettre -> mis, ecrire -> ecrit, lire -> lu, boire -> bu, recevoir -> recu, savoir -> su, pouvoir -> pu, vouloir -> voulu, devoir -> du, courir -> couru, ouvrir -> ouvert, offrir -> offert.

Conjugation of avoir + past participle

Parler (to speak) in the passe compose:

Subject	Form
je	j'ai parle
tu	tu as parle
il / elle / on	il a parle
nous	nous avons parle
vous	vous avez parle
ils / elles	ils ont parle

The participle doesn't change. Avoir is conjugated; parle stays the same for every subject.

Conjugation of etre + past participle

Aller (to go) in the passe compose. With etre, the past participle agrees with the subject in gender and number, like an adjective.

Subject	Form
je (masc)	je suis alle
je (fem)	je suis allee
tu (masc)	tu es alle
tu (fem)	tu es allee
il	il est alle
elle	elle est allee
on	on est alle
nous (masc)	nous sommes alles
nous (fem / mixed)	nous sommes allees
vous (masc sg)	vous etes alle
vous (fem sg)	vous etes allee
vous (masc pl)	vous etes alles
vous (fem pl)	vous etes allees
ils	ils sont alles
elles	elles sont allees

The agreement is the same as any adjective: +e for feminine, +s for plural, +es for feminine plural.

The avoir agreement rule (flagged for attention)

With avoir, the past participle normally doesn't agree with anything. J'ai mange une pomme - no agreement on mange.

But: when a direct object goes before the verb (in the form of an object pronoun, a relative pronoun, or a question word), the past participle agrees with that preceding direct object.

J'ai mange la pomme. (no agreement - object after verb)
Je l'ai mangee. (agreement - "la" pronoun before verb, feminine singular)
Les pommes que j'ai mangees. (agreement - "les pommes" precedes the verb via "que")

This rule is real but unevenly enforced in spoken French. For Foundation tier, recognise it and don't drill it. It matters in writing.

Negation in the passe compose

Ne goes before the auxiliary, pas after it. The participle stays at the end.

Je n'ai pas mange. (I didn't eat.)
Elle n'est pas partie. (She didn't leave.)
Nous ne nous sommes pas couches tard. (We didn't go to bed late.)

Worked examples

Hier, j'ai vu un film au cinema. (Yesterday I saw a film at the cinema.)
Marie est nee a Lyon en 1995. (Marie was born in Lyon in 1995.)
Nous avons mange dans un bon restaurant. (We ate in a good restaurant.)
Ils sont arrives en retard. (They arrived late.)
Elle s'est levee tot ce matin. (She got up early this morning.)
J'ai fait mes devoirs et je suis sorti avec mes amis. (I did my homework and I went out with my friends.)

Common mistakes English speakers make

Defaulting to avoir for every verb: j'ai alle au cinema is wrong, it's je suis alle au cinema. Aller is in the etre set. Forgetting the agreement with etre: elle est alle is wrong, it's elle est allee. And using the wrong irregular participle - j'ai faisi, j'ai etre, j'ai avoi are all wrong; the right forms are j'ai fait, j'ai ete, j'ai eu.