One of the most elegant little structures in Spanish is al + infinitive. It expresses the idea of "upon doing something" or "when doing something," and it's used constantly in both spoken and written Latin American Spanish — often where English would use a when clause or an -ing phrase.
The form: a contraction
Al is actually the contraction of the preposition a + el, the only mandatory contraction in Spanish. In this construction, the el is functioning as an article introducing the infinitive, which is treated as a noun. The whole phrase al entrar literally means something like "at the entering" — but it translates as "upon entering" or "when entering."
Al entrar, vi a María.
Upon entering, I saw María.
When to use it
Use al + infinitive when two actions happen at the same time or in immediate sequence, and the subject of both is either the same or clear from context. It's a quick, clean way to set the scene for the main action.
- Upon / when: Al verlo, me puse feliz. ("Upon seeing him, I felt happy.")
- As soon as: Al oír la noticia, lloró. ("Upon hearing the news, she cried.")
- Every time / whenever (with repeated actions): Al estudiar, pongo música suave. ("When I study, I play soft music.")
Al despertarme, miro el celular.
When I wake up, I check my phone.
Same structure, different translations
Depending on context, al + infinitive can be rendered in English several ways:
| Spanish | Possible English |
|---|---|
| Al salir de la casa… | Upon leaving the house… / When I left the house… / As I left the house… |
| Al verte… | Upon seeing you… / When I saw you… / As soon as I saw you… |
| Al oír el ruido… | When I heard the noise… / At the sound of the noise… |
With pronouns
Object and reflexive pronouns attach to the end of the infinitive, just as they do in other infinitive constructions.
Al levantarme, me lavo la cara.
When I get up, I wash my face.
Al verla, le dije hola.
Upon seeing her, I said hi to her.
The subject doesn't have to be explicit
The subject of the infinitive in al + infinitive is usually understood from context — often it matches the subject of the main clause, but not always. If clarity is needed, a subject pronoun can appear right after the infinitive.
Al entrar yo, ella salió.
As I was entering, she was leaving.
Al + infinitive vs. cuando + clause
You can almost always rephrase al + infinitive with cuando + a full clause, but al + infinitive is tighter and more elegant, and it's much more common in writing and storytelling.
- Al llegar, se quitó los zapatos.
- Cuando llegó, se quitó los zapatos.
Both mean "When he arrived, he took off his shoes." The first sounds slightly more polished; the second is plainer.
In narration
Al + infinitive is a favorite of storytellers because it frames an action quickly without breaking the rhythm of the sentence. You'll see it often in novels, news reports, and spoken anecdotes.
For more on infinitives functioning as nouns — the other role that uses the article el — see the next page.
Related Topics
- The Infinitive: OverviewA1 — The infinitive is the base, uninflected form of a Spanish verb, ending in -ar, -er, or -ir.
- Infinitive after PrepositionsA2 — After a preposition, Spanish always uses the infinitive, never the gerund.
- Infinitive as a NounB1 — In Spanish, the infinitive can function as a noun, often with the article el, and is always masculine singular.