The Spanish past perfect tense is mostly used in the same way as the English past perfect. It expresses what had happened before something else happened:

Ella había estudiado español antes de mudarse a España.

She had studied Spanish before moving to Spain.

The past perfect is formed the same way as the present perfect, i.e. from the auxiliary verb haber and the participle of the main verb. Note that the auxiliary verb haber is in the imperfect tense:

Había dejado las llaves en la oficina.

I had left the keys in the office.

The participle (the main verb of the past perfect and present perfect) is formed as follows:

• verbs ending in –ar (estudiar) get the ending –ado
• verbs ending in –er- and –ir (tener) get the ending –ido

Habías estudiado mucho antes de tomar el examen.

You had studied a lot before taking the exam.

Nunca había tenido un perro antes de adoptar a Max.

I had never had a dog before adopting Max. 

The auxiliary verb haber is conjugated according to the subject (había). Note that the 1st and 3rd person singular forms are the same:

Él no había dicho nada hasta ahora.

He hadn’t said anything until now.

Yo no había comido nada antes de salir.

I hadn’t eaten anything before going out.

The negation no is placed before the auxiliary verb haber (habías) and the participle (pensado). There is never anything between the auxiliary verb haber and the participle:

No habías pensado en las consecuencias.

You had not thought about the consequences.

Nos habíamos escrito muchas cartas antes de conocernos en persona.

We had written many letters to each other before we met in person.

 

The past perfect is often used with the preterite and the imperfect:

Cuando llamaste, ya me había acostado.

When you called, I had already gone to bed.

No me había dado cuenta de lo tarde que era.

I hadn’t realised how late it was.