When forming the passé composé, you already know you need an auxiliary verb plus a past participle. The big question is: which auxiliary? The choice is between avoir (to have) and être (to be).

The rule of thumb is simple: most verbs use avoir. Think of it as the default setting. If you see a verb, your first instinct should be that it pairs with avoir.

J'ai mangé une pomme. (I ate an apple.) Nous avons fini nos devoirs. (We finished our homework.)

These are action verbs, and they take a direct object. You ate something. You finished something. This is the most common pattern in French.

So, when do we use être? There are two main categories of verbs that break the avoir rule. The first and most famous group consists of verbs that usually describe movement or a change of state. Linguists and teachers have developed a handy mnemonic to remember them: DR MRS VANDERTRAMP., an acronym for a list of specific verbs.

Notice the theme? Coming, going, arriving, leaving, being born, dying. These verbs describe a journey or a transformation of the subject itself. This is why they are often called verbs of motion or state change.

Elle est née en 1990. (She was born in 1990.) Ils sont arrivés hier. (They arrived yesterday.)

The second category of verbs that always takes être is much easier to spot: reflexive verbs. These are verbs where the action is done by the subject to itself. You can recognize them by the reflexive pronoun (me, te, se, nous, vous, se) that comes before the auxiliary verb.

The logic is that the subject is undergoing a change of state, even if it's as simple as waking up or washing up. Because the action reflects back on the subject, être is the required auxiliary.

Je me suis levé à 7h. (I got up at 7am.) Elle s'est habillée rapidement. (She got dressed quickly.)

Here's where it gets interesting. A handful of the DR MRS VANDERTRAMP verbs can switch to using avoir. This happens when the verb stops being about the subject's general movement and starts being about the subject acting upon a direct object.. In grammatical terms, the verb becomes transitive.

Let's look at the verb monter (to go up). When you are the one going up, you use être. But when you are taking something else up, you use avoir.

The same logic applies to other verbs like sortir (to go out), descendre (to go down), and passer (to pass).

Je suis sorti. (I went out.) J'ai sorti le chien. (I took the dog out.)

Il est passé par la banque. (He passed by the bank.) Il a passé un bon week-end. (He had a good weekend.)

This isn't an exception to the rule, but a deeper part of it. The choice of auxiliary tells you what kind of action is happening. Être focuses on the subject's journey; avoir focuses on the subject's action on something else.

Time to check your understanding. Let's see if you can pick the correct auxiliary verb in different situations.

Mastering the choice between avoir and être is a huge step in sounding natural in French. It moves from a memorized list to an intuitive understanding of what the sentence is really trying to say.