Beyond habits and descriptions, the imperfect has a third big job: describing actions in progress. If something was happening without a clear beginning or end, or if two actions were unfolding at the same time, the imperfect is the natural choice.
Actions in progress
When you zoom in on a past moment and ask what was happening?, the answer usually comes out in the imperfect. The action has no stated start or finish — it is simply underway.
A las cinco de la tarde, yo estudiaba para el examen.
At five in the afternoon, I was studying for the exam.
Notice the English translations use was doing — the so-called past continuous. Spanish does not need a separate tense for this: the plain imperfect handles it.
Two actions at once: mientras
The word mientras (while) naturally pairs two imperfect verbs, because both actions are in progress simultaneously. Think of it as "action A and action B were both unfolding in the same stretch of time."
Mientras mi papá leía el periódico, mi mamá hablaba por teléfono.
While my dad was reading the newspaper, my mom was talking on the phone.
Los niños dibujaban mientras sus padres preparaban la cena.
The kids were drawing while their parents were preparing dinner.
Interruption: imperfect + preterite
A very common pattern is imperfect + cuando + preterite: an action was already underway (imperfect) when another action suddenly happened (preterite) and interrupted it.
Caminaba por el parque cuando empezó a llover.
I was walking through the park when it started to rain.
Veíamos una película cuando se fue la luz.
We were watching a movie when the power went out.
The imperfect caminaba, veíamos, hablaban sets the background — these were already in progress. The preterite empezó, se fue, entró marks the new event that broke in.
The imperfect progressive
For extra emphasis on the fact that something was in the middle of happening, Spanish also offers the imperfect progressive: estaba + gerundio. Compare:
| Simple imperfect | Imperfect progressive |
|---|---|
| estudiaba | estaba estudiando |
| comía | estaba comiendo |
| vivía | estaba viviendo |
| leíamos | estábamos leyendo |
| jugaban | estaban jugando |
Both forms are grammatically correct. The progressive just adds a little extra stress on the idea that the action was genuinely in progress at a particular moment.
Estaba estudiando cuando me llamaste.
I was studying when you called me.
Los niños estaban jugando afuera cuando empezó la tormenta.
The kids were playing outside when the storm started.
Stacking the scene
In real narration, these patterns mix freely. You can stack multiple imperfects, drop in a preterite, and keep going.
Llovía mucho, todos estaban cansados y nadie hablaba, cuando de repente el tren se detuvo.
It was raining hard, everyone was tired, and nobody was speaking, when suddenly the train stopped.
Three imperfects for background (llovía, estaban, hablaba) and one preterite for the event (se detuvo). This is the rhythm of Spanish storytelling in a single sentence.
A quick checklist for ongoing action
When you are not sure whether to reach for the imperfect, ask yourself three quick questions about the action:
| Question | If yes... |
|---|---|
| Was it already underway at the moment I am describing? | imperfect |
| Is it one of two things happening at the same time? | imperfect |
| Is it the background to a sudden event? | imperfect |
| Did it have a clear start and end? | preterite |
| Was it a single finished event? | preterite |
Common mistakes
❌ Caminé por el parque cuando empezó a llover.
Wrong: the walking was in progress (background) — use the imperfect.
✅ Caminaba por el parque cuando empezó a llover.
Correct: caminaba (imperfect) for the ongoing action; empezó (preterite) for the interruption.
❌ Mientras mi papá leyó el periódico, mi mamá habló por teléfono.
Wrong: simultaneous ongoing actions both need the imperfect.
✅ Mientras mi papá leía el periódico, mi mamá hablaba por teléfono.
Correct: both verbs in the imperfect for two actions happening at once.
❌ Estaba estudiar cuando me llamaste.
Wrong: the progressive needs a gerund, not an infinitive.
✅ Estaba estudiando cuando me llamaste.
Correct: estaba + gerund (-ando/-iendo) for the past progressive.
Finally, look at a surprising use of the imperfect that has nothing to do with the past: politeness.
Related Topics
- Usage: Habitual ActionsA2 — Using the imperfect tense to describe habitual, repeated actions in the past — the equivalent of English 'used to do' and 'would do'.
- Usage: Descriptions and BackgroundB1 — Using the imperfect to describe people, places, emotions, and weather — setting the scene in past narration.
- Imperfect for PolitenessC1 — Using the imperfect tense to soften requests and make questions sound more polite — one of Spanish's most charming grammar tricks.