Preterite vs imperfect: past tenses explained

Spanish has two main past tenses for completed or ongoing events: the preterite (pretérito indefinido) and the imperfect (pretérito imperfecto). Both describe the past, so learners often treat them as interchangeable. They are not.

The core idea: the preterite tells you what happened, as a completed event with a clear beginning or end. The imperfect sets the scene: it describes what was going on, what used to happen, and what things were like.

The preterite: completed actions

Use the preterite for actions that were finished at a specific time, for a specific number of times, or in a sequence.

• Ayer comí paella. (Yesterday I ate paella.)
• Llegamos a las seis. (We arrived at six.)
• Vivió en Sevilla durante tres años. (She lived in Seville for three years.)
• Llovió toda la tarde. (It rained all afternoon.)

Each sentence has an end point: the meal is finished, the arrival happened, the three years are over.

The imperfect: background, habits and ongoing actions

Use the imperfect for descriptions, repeated habits and actions in progress, without a focus on their end.

• Cuando era niño, jugaba al fútbol. (When I was a boy, I played football.) Habit.
• Hacía sol y la gente paseaba. (It was sunny and people were walking.) Description and background.
• Tenía veinte años. (I was twenty.) Age is a state, not an event.
• Mientras cocinaba, escuchaba la radio. (While I was cooking, I was listening to the radio.) Ongoing actions.

Putting them together

Most real sentences combine both. The imperfect gives the background; the preterite gives the event that interrupted it or happened within it.

• Estaba leyendo cuando sonó el teléfono. (I was reading when the phone rang.)
• Llovía cuando salimos. (It was raining when we left.)
• Cuando llegué, todos ya dormían. (When I arrived, everyone was already asleep.)

The reading and the ringing are both past events, but the reading is the setting and the ringing is the interruption.

Verbs that change meaning

Some verbs shift meaning depending on the tense. The preterite marks the moment something happened; the imperfect describes the state that was going on.

Signal words

These words often point one way or the other, but they are clues, not rules:

• Preterite: ayer, anoche, el año pasado, de repente, una vez, en 2010
• Imperfect: siempre, a menudo, todos los días, mientras, cuando era pequeño, de niño

Always check the meaning of the sentence before reaching for a signal word.

Common mistakes

• Using the imperfect for a one-off event. Ayer comía paella sounds like a habit or a scene, not a meal you ate.
• Using the preterite for a habit. Cuando era joven, bailé todos los fines de semana suggests a fixed number of weekends. Use bailaba.
• Forgetting the interruption pattern. Estaba durmiendo cuando sonó el teléfono is natural. Dormí cuando sonó el teléfono is not.

Practice

Choose the correct past tense in each sentence. Look for the event (preterite) or the background (imperfect).

For the other side of the choice, see Ser vs estar, which also depends on whether a description is treated as lasting or as a moment.