Explanation

Many students have trouble knowing when to use the preterite tense or the imperfect tense, as they both refer to actions in the past. There are several general rules you can follow to know when to use one tense or another. Additionally, many Spanish phrases tend to be used only with the preterite or only with the imperfect, so memorizing them is very helpful! In this article, we’ll take a look at the general uses of both tenses, as well as helpful “trigger” phrases.

Pair Work

One way this pair of tenses is often used is to talk about an ongoing action or event that was interrupted in the past. In such case, the interrupted action is given in the imperfect tense, while the interrupting action is given in the preterite.

For example:

examples
Caminaba por el centro cuando me encontré con el hermano de mi mejor amiga. I was walking downtown when I ran into my best friend's brother.
Lourdes y Marco hablaban del examen cuando llegué a clase. Lourdes and Marco were talking about the test when I got to class.

examples

Caminaba por el centro cuando me encontré con el hermano de mi mejor amiga.

I was walking downtown when I ran into my best friend's brother.

Lourdes y Marco hablaban del examen cuando llegué a clase.

Lourdes and Marco were talking about the test when I got to class.

The Preterite

Generally, the preterite is used for completed actions (actions that have definite beginning and end points.) These can be actions that can be viewed as single events, actions that were part of a chain of events, actions that were repeated a very specific number of times, or actions that specifically state the beginning and end of an action.

Check out these examples:

examples
Fui al baile anoche. I went to the dance last night.
Caminé al mercado, compré unos plátanos, y regresé a casa. I walked to the market, bought some bananas, and returned home.
Te llamó tres veces. He called you three times.
Hablé con mi madre de las dos hasta las tres. I spoke with my mother from two o’clock until three o’clock.

Useful Phrases that Trigger the Preterite

There are many helpful words and phrases that indicate specific time frames, therefore signaling that the preterite should be used. Here are a few:

Spanish	English	Spanish	English
una vez	one time	el otro día	the other day
ayer	yesterday	entonces	then
anteayer	the day before yesterday	anteanoche	the night before last
ayer por la mañana	yesterday morning	ayer al mediodía	yesterday at noon
anoche	last night	ayer por la noche	last night
esta mañana	this morning	esta tarde	this afternoon
la semana pasada	last week	el mes pasado	last month
el año pasado	last year	en ese momento	at that moment
ayer por la tarde	yesterday afternoon	hoy por la mañana	this morning
hace (dos) años	(two) years ago	hace (dos) días	(two) days ago
el (lunes) pasado	last (Monday)	la semana pasada	last week
durante (tres) siglos	for (three) centuries	desde el primer momento	from the first moment

Verbs that are Preterite by Nature

Some verbs used to talk about events with a very definite beginning and end are almost always used in the preterite. Here are a few examples.

Spanish	English	Spanish	English
casarse	to get married	graduarse	to graduate
cumplir años	to turn a certain age	llegar	to arrive
darse cuenta de	to realize	morir	to die
decidir	to decide	nacer	to be born
descubrir	to discover	salir	to leave

The Imperfect

The imperfect tense is generally used for actions in the past that do not have a definite end. These can be actions that are not yet completed or refer to a time in general in the past. It can also be used to talk about:

actions that were repeated habitually
actions that set the stage for another past tense event
time and dates
a person’s age in the past
characteristics
mental or physical states

Check out these examples:

examples
Cuando era niña, jugaba con muñecas. When I was a child, I used to play with dolls.
Los chicos hablaban en español. The boys were speaking in Spanish.
Estaba durmiendo cuando el teléfono sonó. I was sleeping when the telephone rang.
Cuando tenía tres años, era muy pequeño. When he was three years old, he was very small.

Useful Phrases that Trigger the Imperfect

Here are some helpful words and phrases that often signal that a verb should be used in the imperfect.

Spanish	English	Spanish	English
a menudo	often	frecuentemente	frequently
rara vez	rarely	a veces	sometimes
generalmente	usually	siempre	always
algunas veces	at times	mientras	while
tantas veces	so many times	todos los años	every year
cada día	every day	muchas veces	many times
todas las semanas	every week	todo el tiempo	all the time
con frecuencia	frequently	casi nunca	almost never
mucho	a lot	nunca	never
por lo general	generally	todos los días	every day
de vez en cuando	once in a while	por un rato	for a while
en aquella época	at that time	varias veces	several times