Lesson 20: Preterite vs. Imperfect

The preterite and the imperfect both describe the past, but they do so in different ways. This lesson will help you understand those differences and choose between them more confidently.

The preterite treats an action as a completed event, often drawing attention to its beginning, end, or result. The imperfect describes actions and situations that were ongoing, repeated, or part of the background. This difference in perspective is called aspect. English shows a similar contrast between "I drove" and "I was driving."

When choosing between them, think about whether you are presenting the action as a completed event or as part of an ongoing situation. The example and diagram below show how the two tenses can work together.

Yo comía un burrito cuando el extraterrestre aterrizó en mi jardín.

I was eating a burrito when the alien landed in my garden.

Here, comía is in the imperfect because "eating the burrito" was already in progress. aterrizó is in the preterite because the alien's landing is a completed event that interrupts the ongoing action. Together, the two tenses create a clear narrative: the imperfect sets the scene for the event, while the preterite moves the story forward.

Now let's take a closer look. These five contrasts will deepen your understanding of how the two tenses differ in common situations.

A Completed Event vs. an Ongoing Action

Preterite

(one time action/event)

Imperfect

(ongoing action/event)

El gato saltó sobre la valla.

The cat jumped over the fence.

El gato dormía bajo el sol.

The cat was sleeping in the sun.

The cat jumping over the fence is a singular, one-time event, making the preterite the appropriate choice. The cat sleeping in the sun, by contrast, is an ongoing action, so the imperfect conveys its continuous aspect.

A Single Event vs. a Habitual Action

Preterite

(one time action/event)

Imperfect

(ongoing action/event)

Anoche vimos una estrella fugaz.

Last night we saw a shooting star.

Mirábamos las estrellas cada noche.

We used to look at the stars every night.

The sighting of the shooting star is a distinct event that occurred at a specific moment, so it uses the preterite. On the right, the action is habitual or repeated without a specified frequency, making the imperfect the right choice for that ongoing, repeated nature.

A Sequence of Events vs. Simultaneous Ongoing Actions

Preterite

(one time action/event)

Imperfect

(ongoing action/event)

Cerré mi libro, luego fui a encender el fuego.

I closed my book, then went to light the fire.

Leía un libro mientras el fuego me calentaba.

I read a book while the fire warmed me.

Closing the book and then lighting the fire are sequential, one-time events; the preterite is appropriate. Reading and being warmed by the fire, however, happen simultaneously and are ongoing, so the imperfect is needed.

A Change in State vs. an Ongoing State

Preterite

(one time action/event)

Imperfect

(ongoing action/event)

Ella se puso feliz cuando recibió las flores.

She was happy when she received the flowers.

Ella estaba feliz en la fiesta.

She was happy at the party.

On the left, she experiences a change in her emotional state because of a specific event, which calls for the preterite. On the right, her happiness is continuous, with no change in state, so the imperfect describes her ongoing emotion.

A Defined Duration vs. an Open-Ended Situation

Preterite

(one time action/event)

Imperfect

(ongoing action/event)

Viajé por Europa durante un mes.

I traveled around Europe for a month.

Viajaba por Europa.

I used to travel around Europe.

On the left, the traveling has a defined duration of one month, establishing a clear endpoint—that specificity calls for the preterite. On the right, traveling through Europe lacks a definitive timeline or conclusion, making the imperfect more suitable for its indefinite, ongoing nature.

With a few common verbs, choosing the preterite or imperfect can significantly change the meaning expressed in English. The examples below show how each tense presents the verb differently.

Poder: succeeded vs. could / used to be able to

Preterite

(one time action/event)

Imperfect

(ongoing action/event)

Yo pude llegar a la cima.

I managed to get to the peak.

Yo podía llegar a la cima.

I used to be able to get to the peak.

In the preterite form, poder indicates a specific instance of achieving or succeeding in an action. This contrasts with its imperfect form, which refers to a general ability or possibility in the past, without a specific event in focus.

Querer: tried vs. wanted

Preterite

(one time action/event)

Imperfect

(ongoing action/event)

Ella quiso ayudarme a estudiar.

She tried to help me study.

Ella quería ayudarme a estudiar.

She wanted to help me study.

The preterite tense of querer implies an attempt or effort, focusing on the action rather than the desire. On the other hand, the imperfect form expresses a past desire or intention, emphasizing the feeling or intention over the specific action.

Saber: found out vs. used to know

Preterite

(one time action/event)

Imperfect

(ongoing action/event)

Yo supe quién es mi abuela.

I found out who my grandmother is.

Yo sabía de memoria los cuentos de mi abuela.

I used to know my grandmother's stories by heart.

Saber in the preterite is used for a specific moment of learning or realization. In contrast, the imperfect form suggests a continuous state of knowledge or awareness over time without pinpointing when this knowledge was acquired.

Conocer: met vs. knew

Preterite

(one time action/event)

Imperfect

(ongoing action/event)

Conoció a su compañero de cuarto cuando se mudó a su dormitorio.

He met his roommate when he moved into his dorm.

Conocía a su compañero de cuarto desde que eran niños.

He knew his roommate since they were children.

In its preterite form, conocer describes a first-time encounter. The imperfect tense indicates an ongoing acquaintance or familiarity, suggesting a prior and continuous relationship.

With practice, these differences will become easier to recognize. Remember that the surrounding context helps determine how each verb should be understood.