The past progressive describes an action in progress at a specific moment in the past. It highlights the continuity, the duration, or the background of a past situation, and not its final result. It is also used to show two actions that were happening at the same time or to present a long action interrupted by another, more instantaneous, one. In Brazilian Portuguese, the most common form is with the Verbal Gerund and Auxiliary Verbs.

The formation begins with the auxiliary estar in the imperfect. This verb carries the temporal marker of the past and agrees with the subject. The form of the auxiliary comes before the gerund and builds the progressive value of the clause.

The regular gerund is formed from the endings of the infinitive: -ar verbs become -ando, -er verbs become -endo, and -ir verbs become -indo. This gerund expresses the action in progress, without indicating completion. In many contexts, it appears after the Imperfect of the auxiliary estar.

Some very frequent verbs use irregular or lexicalised gerund forms. These forms should be recognised as part of the normal use of the language. Among the most common are verbs of movement, of placement, and of performing an action.

The past progressive focuses on the process instead of the conclusion. Therefore, it appears when the attention is on the action in progress, on its duration, or on the context that surrounds it. It can also mark simultaneity between past events, showing that one action occurred while another was unfolding.

In Brazilian Portuguese, the sequence estar + gerund is very productive and natural in speech and writing. In European Portuguese, it is more common to use estar a + infinitive in many equivalent contexts. The two constructions express progression, but belong to different regional preferences.

This tense contrasts with the simple past, because the simple past presents the action as completed and the progressive presents it as ongoing. It also resembles the imperfect, but the progressive is more specific in the idea of explicit continuity. Stative verbs like saber and gostar rarely appear in this form, because they normally describe a state rather than a process.

The past progressive is the past tense form that foregrounds the duration of an action, its development, or its background role for another event. It is formed with estar in the imperfect plus the gerund, regular or irregular, and in Brazilian Portuguese this structure is the most common. In European Portuguese, the same notion often appears with estar a plus the infinitive. The choice between progressive and perfect depends on whether one wants to show process or result.