An auxiliary is a verb that is used to construct another verb form. It does not carry the main idea of the action on its own. In a sentence like j’ai parlé, the important action is parlé and the auxiliary avoir serves to place this action in a compound tense. Auxiliaries also appear in other constructions, for example with a past participle or with an infinitive. They give the sentence its tense, aspect or grammatical structure.

Uses of the auxiliary avoir

Usage	Explanation
Common compound tenses	We use avoir to form most compound tenses with an action verb.
Ordinary actions	We choose avoir when the verb mainly tells what happens and not a change of state.
Verbs with a complement	We often use avoir with verbs that take a direct object.

Avoir is the most common auxiliary in French. It is used with most verbs to form the passé composé, the pluperfect, the anterior future and the past conditional. The form is constructed with conjugated avoir + past participle of the main verb. We say j’ai mangé, nous avions fini, elle aura compris, vous auriez répondu. The main verb remains in the past participle, as in Past Participle.

Uses of the auxiliary être

Usage	Explanation
Movement	We use être with many verbs that express movement or arrival.
Change of state	We choose être for verbs that show that a situation changes.
Pronominal verbs	We often use être with pronominal verbs.

Être is used as an auxiliary with several movement verbs such as aller, venir, arriver, partir, entrer and sortir. It is also used with verbs that express a change of state, such as naître, mourir, devenir and tomber. With many pronominal verbs, the auxiliary is also être, for example se lever, se laver, s’habiller. The general form is conjugated être + past participle.

Rules for choosing the auxiliary

Idea
We choose avoir with most action verbs.
We choose être with many movement or state-change verbs.
We often choose être with pronominal verbs.

The choice depends on the verb and its construction. Verbs that express movement, entry into a place, an exit, a change of state or movement toward another state often take être. Most other verbs take avoir. Some verbs change auxiliaries according to their meaning. Sortir takes être in il est sorti, but avoir in il a sorti la voiture. Monter, descendre, passer, rentrer and retourner follow the same type of contrast. The verb constructions studied in Verb Constructions often show these differences.

Past participle agreement with être

Idea
With être, the past participle agrees with the subject in feminine singular.
With être, the past participle agrees with the subject in plural.

With être, the past participle agrees with the subject. Add e for the feminine singular, s for the masculine plural, and es for the feminine plural. We say elle est arrivée, ils sont partis, elles sont parties. The past participle therefore changes according to the gender and number of the subject, as in Past Agreement.

Past participle agreement with avoir

Idea
With avoir, the past participle is generally invariable.
With avoir, the past participle agrees if the direct object is placed before the verb.

With avoir, the past participle generally remains unchanged. We say j’ai parlé, nous avons fini, ils ont vendu. Agreement appears only if the direct object is placed before the verb. We say les lettres que j’ai écrites, la robe qu’il a achetée. When the direct object is after the verb, there is no agreement. We say j’ai écrit les lettres.

Verb	Subject	Infinitive	Conjugation
conditionnel présent	je	être
futur simple	je	avoir
passé composé	je	être
présent	je	avoir
passé composé	je	avoir
présent	je	être
futur simple	je	être
conditionnel présent	je	avoir

Essential forms of être and avoir

Subject	Infinitive	Conjugation
je	être	suis
je	avoir	ai
je	être	ai été
je	avoir	ai eu
je	être	serai
je	avoir	aurai
je	être	serais
je	avoir	aurais

Scramble

In the present tense, être gives je suis, tu es, il est, nous sommes, vous êtes, ils sont. Avoir gives j’ai, tu as, il a, nous avons, vous avez, ils ont. In the passé simple, we encounter je fus and j’eus in written narratives. In the future, être gives je serai, tu seras, il sera, nous serons, vous serez, ils seront and avoir gives j’aurai, tu auras, il aura, nous aurons, vous aurez, ils auront. In the conditional, être gives je serais, tu serais, il serait, nous serions, vous seriez, ils seraient and avoir gives j’aurais, tu aurais, il aurait, nous aurions, vous auriez, ils auraient.

Verb	Subject	Infinitive	Conjugation
passé composé	nous	avoir
futur antérieur	vous	avoir
plus que parfait	elle	être

Auxiliaries in compound tenses

Subject	Infinitive	Conjugation
nous	avoir	avons chanté
elle	être	était partie
vous	avoir	aurez fini

Scramble

In a compound tense, the auxiliary carries the tense and person, while the main verb remains in the past participle. We therefore obtain a structure like conjugated auxiliary + past participle. The passé composé often expresses an action completed in the present being narrated. The pluperfect places this action before another past moment. The anterior future presents an action completed in the future. The past conditional is often used to talk about a hypothetical action that has already been completed. With regular and irregular verbs, the form of the past participle comes from the main verb, as in Regular Verbs and Irregular Verbs.

Common constructions with auxiliaries

Usage	Explanation
Action in progress	We use être en train de to emphasize an action happening now.
Past recent	We use venir de to say that an action just occurred.
Futur proche	We use aller plus an infinitive to talk about a very near action.

French also uses constructions close to the auxiliary to express an action in progress, the recent past and the near future. Être en train de + infinitive emphasizes an action in progress, as in je suis en train de lire. Venir de + infinitive expresses a very recent past, as in nous venons d’arriver. Aller + infinitive is used for the near future, as in elle va partir. These constructions do not function like a traditional compound tense, but they place the action in time with a stable verb structure. Verbs such as aller and venir are among the frequent forms to recognize in Irregular Verbs.

Verb	Subject	Infinitive	Conjugation
présent	je	venir
présent	tu	être
présent	il	venir
présent	nous	avoir
présent	il	aller
présent	tu	avoir
présent	nous	être
présent	je	aller

Useful forms of frequent verbs

Subject	Infinitive	Conjugation
je	aller	vais
je	venir	viens
tu	être	es
tu	avoir	as
il	aller	va
il	venir	vient
nous	être	sommes
nous	avoir	avons

Scramble

Être, avoir, aller and venir appear everywhere in French. Être is used for existence, state, identification and as an auxiliary. Avoir is used for possession, age, certain expressions and as an auxiliary. Aller is used for movement and for the near future. Venir is used for arrival, origin and the recent past. These verbs recur in simple sentences, in compound tenses and in several common constructions, which makes them essential to recognize quickly.