Forming the Imperfect Subjunctive

The imperfect subjunctive is the past-tense counterpart to the present subjunctive: the mood Spanish reaches for when a wish, doubt, request or hypothesis is anchored in the past, and the workhorse of si clauses (si tuviera dinero...) and the polite quisiera. All of that - the when and the why - belongs to a sister page. This page is about the machinery, and the machinery is a gift.

There is really only one thing to learn: build it from the preterite. Get that, and the tense that scares people turns out to have no independent irregulars at all.

The one rule: third-person plural preterite, minus -ron

Every imperfect subjunctive is built from the ellos/ellas form of the preterite, with the final -ron removed. That stem carries all six persons.

• hablar -> ellos hablaron -> stem habla-
• comer -> ellos comieron -> stem comie-
• vivir -> ellos vivieron -> stem vivie-

Whatever the preterite did, the stem keeps. This is the whole trick, and it is why the -ir and -er families end up looking identical from here on.

Two ending sets, both correct

Now the endings. Spanish gives you two full sets for this tense, and they mean exactly the same thing. Add either to the stem.

The same for the other two families, which share one shape:

Two things to flag. The yo and él/ella/usted forms are identical (hablara / hablara), exactly as in the present subjunctive; context sorts it out. And the nosotros form always carries a written accent - habláramos, hablásemos, comiéramos, viviésemos - because the stress falls back one syllable from the rest of the set. Leave it off and you have misspelt the word; it is not decorative.

-ra or -se: which to use

Since they are interchangeable, the honest answer is: use whichever you like, and be consistent within a sentence. But they are not evenly distributed, so here is the steer worth taking.

• The -ra forms are the everyday default. They dominate in speech, they are far and away the more common in Latin America, and if you only want to learn one set, learn this one.
• The -se forms lean literary and formal. They survive most strongly in written prose and in Peninsular Spanish, where a novel or an editorial will happily write hablase, tuviese, fuese.

My advice, flatly: speak -ra, and simply recognise -se when you read it, until your ear is comfortable enough to reach for it. There is one job the -ra form can do that -se cannot - standing in for the pluperfect indicative in formal writing (el hombre que fuera presidente, for who had been president) - but that is a flourish, not a rule you need on day one.

It inherits every preterite irregularity

Here is the payoff for building from the preterite: the imperfect subjunctive has no irregulars of its own. Every "irregular" form is just the irregular preterite stem with the endings bolted on. Learn the preterite once and you get this tense free.

A couple of things worth noticing. Ser and ir share a preterite (fueron), so they share an imperfect subjunctive too: fuera can be were or went, and only context tells you which. The -j- stem verbs (dijeron -> dijera, trajeron -> trajera, condujeron -> condujera) drop the i of the ending - it is dijeran, never "dijieran" - but that is already baked into the preterite you copied, so you do not have to think about it. And hubiera is the one to hold onto: it is the auxiliary you need to build the pluperfect subjunctive (si hubiera sabido..., if I had known...) later on.

Where you will actually meet it

Formation done, here is the signpost so the forms have somewhere to go. The imperfect subjunctive turns up in three main places, all covered on their own pages:

• Past-tense subjunctive triggers. When the main verb that would take a present subjunctive is itself in the past, the subordinate verb slides back: Quiero que vengas becomes Quería que vinieras (I wanted you to come). Era importante que estudiaran. (It was important that they studied.)
• si clauses about the unreal. For hypotheticals that are contrary to fact, si takes the imperfect subjunctive and the other half takes the conditional: Si tuviera dinero, viajaría por el mundo. (If I had money, I would travel the world.) This is the big one, and it has its own si clauses page.
• The polite quisiera. Quisiera is a softened, more courteous I would like: Quisiera un café, por favor. (I would like a coffee, please.) It is the imperfect subjunctive of querer doing duty as good manners.

Worked examples

• Si yo fuera rico, no trabajaría. (If I were rich, I would not work.) - fuera, from fueron.
• No había nadie que pudiera ayudarnos. (There was nobody who could help us.) - pudiera, from pudieron.
• Me pidió que le dijera la verdad. (He asked me to tell him the truth.) - dijera, the -j- stem.
• ¿Quisieras venir conmigo? (Would you like to come with me?) - the polite quisiera.
• Ojalá tuviéramos más tiempo. (If only we had more time.) - note the nosotros accent, tuviéramos.
• Era natural que estuviese nervioso. (It was natural that he was nervous.) - the -se form, formal register.

Common mistakes English speakers make

Forgetting the nosotros accent. Writing hablaramos or tuvieramos without the accent is the single most frequent slip. The stress is on the third syllable from the end: habl-Á-ra-mos, tuv-IÉ-ra-mos. The accent is compulsory - habláramos, tuviéramos, hubiésemos - every time.

Building from the wrong stem. The tense grows from the ellos preterite, not the infinitive and not the yo-form. If you start from tener you will invent "teniera"; start from tuvieron and you get the correct tuviera. When an irregular form looks wrong, check the preterite you copied it from.

Mixing -ra and -se in one form. Both sets are fine, but pick one and stay in it. "Hablarasemos" is not a word; it is habláramos or hablásemos, never a splice of the two.

"Un-irregularising" the -j- stems. Because dijeron and trajeron drop the i, the subjunctive keeps it dropped: dijeran, trajeran, condujeran, never "dijieran". You copied it correctly from the preterite - do not add the i back.

Get the third-person-plural-preterite rule straight, remember the nosotros accent, and the imperfect subjunctive is genuinely one of the tidiest tenses in Spanish. The real work is not building it - it is knowing when the sentence demands it, and that is the next page.

See also

• Forming the present subjunctive - the present-tense partner, built from the yo-form with the opposite-vowel rule; the same mood, a different stem trick.
• si clauses - the unreal conditional, where si tuviera... viajaría pairs this tense with the conditional; the single most common home of the imperfect subjunctive.
• The Spanish verbs page lists each verb's preterite alongside its imperfect subjunctive, so you can see the stem it comes from.
• The Spanish grammar cheatsheet has both ending sets and the irregular stems on one card.