Forming the Imperfect Subjunctive in Spanish

Forming the imperfect subjunctive (el pretérito imperfecto de subjuntivo) in Spanish is based on a regular, consistent rule. To conjugate any verb, whether regular or irregular, you must start with the third-person plural form of the preterite tense (Pretérito Indefinido). For example, 'hablar' becomes 'hablaron', 'comer' becomes 'comieron', and 'ir/ser' becomes 'fueron'. You then drop the ending '-ron' to find the base. Finally, you attach the subjunctive endings. There are two sets of endings: the '-ra' set (hablara, hablaras) and the '-se' set (hablase, hablases). Both sets are grammatically correct and interchangeable, though the '-ra' set is much more common in everyday spoken Spanish.

The endings for the '-ra' set are: -ra, -ras, -ra, -ramos, -rais, -ran. The endings for the '-se' set are: -se, -ses, -se, -semos, -seis, -sen. A key orthographic detail to remember is that the first-person plural form (nosotros) always requires a written accent on the vowel immediately preceding the ending, as in 'habláramos' or 'hablásemos'. Since the base is taken from the preterite form, any stem changes or irregularities present in the preterite carry over to the imperfect subjunctive. This makes learning preterite irregularities essential for mastering the past subjunctive.