An Overview of the Past Perfect Subjunctive:

The past perfect subjunctive is used in the same way as the past perfect to refer to a previous event with relevance for another past event. The difference is the past perfect subjunctive is preceded by a subjunctive trigger, e.g.: Prefería que no hubiera comprado ese suéter. It is also used to express the meaning "should/would have+past participle", e.g.: Yo hubiera escrito una carta a mi abuelita pero no tuve tiempo.

How to Form the Past Perfect Subjunctive

The past perfect subjunctive is formed by using the imperfect subjunctive form of the auxiliary haber and a past participle, e.g.: Fue horrible que no hubieran aprendido la verdad.

The following table shows the different subject forms of haber with the past participle of decir.

How to Use the Past Perfect Subjunctive

Just as other forms of the subjunctive, the past perfect subjunctive is required in the presence of particular "triggers". Here are some of the most common verbs that trigger past perfect subjunctive when they are conjugated in the past (preterite or imperfect): querer que, gustar que, dudar que, lamentar que, e.g.: Queríamos que nos hubiéramos quedado en la playa.

Here are some common verbs that trigger the past perfect subjunctive when in the past (preterite or imperfect):

• dudar que, desear que, esperar que, exigir que, gustar que, insistir que, necesitar que, pedir que, preferir que, prohibir que, proponer que, querer que, recomendar que, sugerir que, temer que, e.g.: Jorge dudaba que el político hubiera dicho la verdad. ("Jorge doubted that the politician would have told the truth.")

Other expressions that trigger the subjunctive in the subordinate clause are:

• fue/era bueno que, fue/era dudoso que, fue/era importante que, fue/era mejor que, fue/era necesario que, fue/era preferible que, fue/era una lástima que, tenía/tuve miedo de que, para que, a menos que, en caso (de) que, antes (de) que, sin que, e.g.: Era importante que ustedes hubieran llegado a tiempo. ("It was important that you had arrived on time.")

The Past Perfect Subjunctive in si Clauses 

The past perfect subjunctive is also required after si when the conditional perfect is in the main clause, e.g.: No me habría hecho un tatuaje si hubiera costado más de $100. Remember that it is always the past perfect subjunctive that occurs after si while the conditional perfect NEVER occurs after si.

The Past Perfect Subjunctive to Express "would/should have"

The past perfect subjunctive is also used to express the meaning "would/should have+past participle", e.g.: Tú hubieras traído comida al parque ("You should have brought food to the park.")