Estar + gerundio

The construction estar + gerundio combines a conjugated form of estar with the gerund (the -ando / -iendo form of a verb) to describe an action that is in progress at a specific moment. It is the direct equivalent of the English continuous tenses: «I am reading», «we were sleeping». The gerund itself never changes form to agree with the subject — only estar is conjugated.

• Action in progress right now. Use the present continuous (estoy / estás / está… + gerund) when the action is happening at the moment of speaking: «Estoy comiendo» (I am eating right now).

• Action in progress at a past moment. Use the past continuous (estaba / estabas / estaba… + gerund) when the action was ongoing at a specific point in the past, often interrupted by another event: «Estábamos durmiendo cuando sonó el teléfono».

• Contrast with the simple present. The simple present («Leo un libro») states a general habit or fact. The continuous («Estoy leyendo un libro») stresses that the reading is happening at this very moment.

The gerund is formed by removing the infinitive ending and adding -ando (-ar verbs) or -iendo (-er / -ir verbs).

y-insertion. When the stem of an -er or -ir verb ends in a vowel, the -iendo ending would create a three-vowel cluster. Spanish inserts a y to break it up, giving -yendo.

Stem-changing verbs (-ir only). Stem-changing -ir verbs carry their stem change into the gerund. The vowel shift is e → i or o → u.

Conjugating estar. Pair the gerund with the correct form of estar. Below are the present and imperfect forms used with this construction.

Pronoun placement. Object pronouns can either go before the conjugated estar or be attached to the end of the gerund. Both positions are correct. When a pronoun is attached, a written accent is added to preserve the original stress: lo estoy leyendo = estoy leyéndolo. With two pronouns attached, the accent is still required: leyéndosela.

• Forgetting y-insertion: *leendo → leyendo.

  When the stem of an -er or -ir verb ends in a vowel, the gerund ending -iendo becomes -yendo. The form *leendo is not Spanish. The correct form is leyendo. The same rule applies to oír → oyendo, traer → trayendo, and similar verbs.

• Missing the stem change: *pediendo → pidiendo, *dormiendo → durmiendo.

  Stem-changing -ir verbs change their stem vowel in the gerund just as they do in the third-person preterite. *pediendo and *dormiendo are incorrect. The correct forms are pidiendo (e → i) and durmiendo (o → u). This change only affects -ir verbs, not -er verbs.

• Dropping the accent with attached pronouns: *leyendosela → leyéndosela.

  Attaching one or more pronouns to a gerund shifts the word's length, so a written accent must be added to keep the stress on the correct syllable. *leyendosela is missing its accent. The correct form is leyéndosela. The same applies to a single attached pronoun: leyéndolo, not *leyendolo.