The past perfect subjunctive, or pluperfect subjunctive (el pluscuamperfecto de subjuntivo ), is used to talk about hypothetical situations in the past, past conditionals, and past actions that preceded other past actions.

Past Perfect Subjunctive Forms

The past perfect subjunctive is formed with the imperfect subjunctive of the verb haber and a past participle.

Past Perfect Subjunctive Formula:

imperfect subjunctive of haber + past participle

Imperfect Subjunctive of Haber

Hubiera vs. Hubiese

The imperfect subjunctive of haber can be conjugated in two different ways. Both are correct, though use of the first, whose yo form is hubiera, is more widespread.

Subject	Imperfect Subjunctive 1	Imperfect Subjunctive 2
yo	hubiera	hubiese
tú	hubieras	hubieses
él/ella	hubiera	hubiese
usted	hubiera	hubiese
nosotros	hubiéramos	hubiésemos
vosotros	hubierais	hubieseis
ellos/ellas	hubieran	hubiesen
ustedes	hubieran	hubiesen

Past Perfect Subjunctive Uses

The past perfect subjunctive is commonly used to talk about past hypotheticals, conditionals, and past actions preceding other past actions.

1. Hypotheticals

The past perfect subjunctive is commonly used to talk about hypothetical situations, especially those relating to regrets or hindsight.

examples
Ojalá que hubiera/hubiese sabido. I wish I had known.
¿Y si Don Quijote hubiera/hubiese tenido razón sobre los molinos? What if Don Quijote had been right about the windmills?

2. Conditionals

The past perfect subjunctive is used along with the conditional perfect to talk about conditionals in the past.

examples
Si hubiera/hubiese sabido, habría venido. If I had known, I would have come.
Si hubiera/hubiese tenido más dinero, habría comprado el cuadro que vimos en el mercado. If I'd had more money, I would've bought the painting we saw in the market.

3. Actions Preceding Other Past Actions

The past perfect is used along with the simple past or imperfect to talk about a past action that preceded a second past action. Whichever of these events is the furthest back in the past is talked about with the past perfect subjunctive.

examples
Pablo dudó que yo hubiera/hubiese ido a Perú. Pablo doubted that I had been to Peru.
Mamá no creyó que hubieras/hubieses limpiado el cuarto. Mom did not believe that you had cleaned the room.
El policía buscaba a algún testigo que hubiera/hubiese visto el robo. The police officer was looking for a witness who had witnessed the robbery