The preterit and imperfect are two distinct past tense forms in Spanish used to describe completed and ongoing or habitual actions, respectively. The preterit marks a single, finished event-like "I ate dinner"-while the imperfect describes repeated, continuous, or background actions-such as "I was eating dinner" or "I used to eat dinner at 7."
These tenses are not interchangeable. Using the wrong one changes the meaning of a sentence. For example, "Ayer comí una manzana" (I ate an apple yesterday) uses the preterit to mark a specific, completed action. "Cuando era niño, comía manzanas todos los días" (When I was a child, I used to eat apples every day) uses the imperfect to show a repeated habit.
Both tenses are formed from the same stem-the root of the verb-but with different endings. The preterit uses regular endings (-é, -aste, -ó, etc.) for -ar, -er, and -ir verbs. The imperfect uses endings like -aba, -abas, -aba, -ábamos, -abais, -aban. For example, hablar (to speak): hablé (I spoke), hablaba (I was speaking or I used to speak).
The preterit is used for actions with a clear beginning and end. It's common for events that happened once and are now finished. This includes actions tied to specific times: "El partido empezó a las siete" (The game started at seven). It's also used for sudden or completed events: "Se cayó del banco" (He fell off the bench).
The imperfect describes ongoing states, habitual actions, or background descriptions. It's often used in storytelling to set the scene. For example: "Era un día frío y llovía" (It was a cold day and it was raining). Here, "era" (was) and "lluvia" (rained) are imperfect because they describe conditions, not single events.
Use the imperfect for age, time, weather, emotions, and descriptions. "Tenía ocho años cuando empecé a estudiar" (I was eight years old when I started studying). "Mi madre me miraba con tristeza" (My mother looked at me sadly). These are not one-time events-they're states or feelings that lasted over time.
Regular -ar verbs in the preterit follow the pattern: -é, -aste, -ó, -amos, -aron. For example, hablar: hablé, hablaste, habló, hablamos, hablaron. The imperfect adds -aba, -abas, -aba, -ábamos, -abais, -aban. So hablar becomes hablaba, hablabas, etc.
For -er and -ir verbs, the preterit endings are similar: -í, -iste, -ió, -imos, -ieron. For example, comer: comí, comiste, comió, comimos, comieron. The imperfect uses -ía, -ías, -ía, -íamos, -íais, -ían. So comer becomes comía, comías, etc.
There are irregular verbs in both tenses. For example, ir (to go) in the preterit: fui, fuiste, fue, fuimos, fueron. In the imperfect: iba, ibas, iba, íbamos, ibais, iban. The verb ser (to be) is irregular in both: fue (preterit), era (imperfect).
| Verb | Preterit | Imperfect |
|---|---|---|
| hablar (to speak) | hablé | hablaba |
| comer (to eat) | comí | comía |
| ser (to be) | fue | era |
| ir (to go) | fui | iba |
Many learners mix up the preterit and imperfect because both refer to the past. A frequent error is using the preterit for habitual actions. For example, "Cuando era niño, jugaba fútbol todos los días" is correct in the imperfect. Using "jugué" would imply a single, completed game, not a daily habit.
Another mistake is applying the preterit to background scenes in narratives. In stories, setting details-time of day, weather, emotional state-are usually in the imperfect. "Eran las nueve de la noche y llovía" (It was nine o'clock and it was raining) sets the mood correctly with the imperfect.
A non-obvious rule: when two actions happen simultaneously, the imperfect often describes the longer or ongoing one. For example: "Mientras estudiaba, mi hermano llegó a casa" (While I was studying, my brother arrived home). "Estudiaba" is imperfect (ongoing), "llegó" is preterit (completed event).
Consider this narrative: "Era un viernes por la tarde. Mi amigo y yo caminábamos por el parque. De repente, empezó a llover. Corrimos hacia la cafetería. Nos sentamos en una mesa cerca de la ventana. Hablamos durante dos horas."
Breakdown: - "Era un viernes" - imperfect (time setting) - "camínábamos" - imperfect (continuous action) - "empezó a llover" - preterit (sudden event) - "corrimos" - preterit (completed action) - "nos sentamos" - preterit (single event) - "hablamos" - preterit (specific duration)
This sequence shows how the two tenses work together. The imperfect establishes the atmosphere and ongoing actions. The preterit punctuates key moments.
I once taught a student who wrote: "Me desperté a las siete y me vestí. Luego, salí a caminar." The verb "salí" is correct in the preterit-it's a single departure. But "me vestí" is also correct because it's a completed routine. However, if the student had said "me vestía cada mañana," that would be imperfect-habitual action.
Use the preterit for: - Single completed actions ("Escribí una carta") - Events with a clear start and end ("Nació en 1990") - Sudden changes ("Se rompió el vaso") - Actions tied to specific times ("Comí en el restaurante a las ocho")
Use the imperfect for: - Repeated or habitual actions ("Jugaba al fútbol todos los fines de semana") - Ongoing states ("Estaba cansado") - Time, weather, age, and descriptions ("Eran las diez") - Background settings in stories ("La casa era vieja y oscura")
Some verbs are almost always in the imperfect: querer (to want), poder (to be able to), deber (to owe), tener (to have), estar (to be). For example: "Quería ir al cine" (I wanted to go to the movies)-not "quise" unless it's a single decision.
The core difference lies in whether the action is seen as complete or ongoing. The preterit treats the action as a unit: "Lo terminé" (I finished it). The imperfect sees it as extended: "Lo estaba terminando" (I was in the process of finishing it).
Even when describing the same event, the choice changes the nuance. "Mi hermana se fue" (She left) implies a single, finished act. "Mi hermana se iba" (She was leaving) suggests a gradual or uncertain departure.
According to the Real Academia Española (RAE), the imperfect is used to express "acciones pasadas que no tienen un límite temporal definido" (past actions without a defined time limit). The preterit is for "acciones que tienen un inicio y un fin determinados" (actions with a defined start and end).