As is the case with some of the other conjugation forms, the imperfect indicative forms are made by removing the infinitive ending of the verb (-ar, -er or -ir) and replacing it with an ending that indicates who is performing the action of the verb.

To take one example, the infinitive form of the verb that means "to speak" is hablar. Its infinitive ending is -ar, leaving the stem of habl-. To say "I was speaking," add -aba to the stem, forming hablaba. To say "you were speaking" (singular informal), add -abas to the stem, forming hablabas. Other forms exist for other persons. (Note: In this lesson, the forms "was speaking," "was learning" and so on are used to translate the imperfect indicative. Other translations also could be used, such as "used to speak" or even "spoke." The translation used depends on the context.)

The endings are quite different for verbs that end in -er and -ir, but the principle is the same. Remove the infinitive ending, then add the appropriate ending to the remaining stem.

The following chart shows the conjugations for each of the three infinitive types. The added endings for each verb are indicated in boldface.

As you may notice, the -er and -ir verbs follow the same pattern in the imperfect indicative. Also, the first- and third-person singular forms (the "I" and "he/she/it/you" forms) are the same. Thus hablaba could mean "I was speaking," "he was speaking," "she was speaking," "it was speaking" or "you were speaking." If the context doesn't otherwise indicate, a pronoun or subject noun is used before the verb in such cases to indicate who is performing the action.

Note also that the conjugations above are for verbs that follow the regular conjugation. Fortunately, very few verbs are irregular in this tense.