como si + Imperfect Subjunctive

As if Construction

Level 4

Use 'como si' followed by the imperfect subjunctive to make a comparison to an unreal or hypothetical situation.

How It Works

The structure 'como si' is used to describe a situation by comparing it to something unreal, hypothetical, or imaginary. It's the direct equivalent of 'as if' in English.

Key Rule: The verb that follows 'como si' is normally in the imperfect subjunctive for a situation happening at the same time as the main clause, no matter what tense that main clause is in. If the 'as if' action happened earlier, use the pluperfect subjunctive (hubiera/hubiese + participle) instead, as in the last example below.

The structure is:
Main Clause + como si + Imperfect Subjunctive Clause

Let's see how this works with different tenses in the main clause:

  • Present Main Clause:
    Gasta dinero como si fuera rico. (He spends money as if he were rich.)
    He isn't rich, but his spending is like that of a rich person.
  • Past (Preterite) Main Clause:
    Reaccionó como si no supiera nada. (He reacted as if he knew nothing.)
    He probably knew something, but his reaction suggested otherwise.
  • Past (Imperfect) Main Clause:
    Siempre caminaba como si tuviera prisa. (He always walked as if he were in a hurry.)
    This describes a habitual past action compared to a hypothetical state.
  • Conditional Main Clause:
    Yo te trataría como si fueras de la familia. (I would treat you as if you were family.)
    This sets up a hypothetical treatment based on a hypothetical relationship.

Remember that the imperfect subjunctive has two forms (-ra and -se). Both are correct, though the -ra form is more common in speech.
Habla como si lo supiera todo. = Habla como si lo supiese todo.

Examples (5)

  1. Habla español como si fuera nativo.

    He speaks Spanish as if he were a native speaker.

    Word by Word: He speaks Spanish as if he were native.

  2. Me miró como si no me conociera.

    She looked at me as if she didn't know me.

    Word by Word: She looked at me as if not me she knew.

  3. Gastaron todo su dinero como si no hubiera un mañana.

    They spent all their money as if there were no tomorrow.

    Word by Word: They spent all their money as if not there were a tomorrow.

  4. Actúas como si no te importara nada.

    You act as if nothing mattered to you.

    Word by Word: You act as if not to you it mattered nothing.

  5. Llegó a la fiesta como si no hubiera pasado nada.

    He arrived at the party as if nothing had happened.

    When the 'as if' action refers to something that would have happened before the main verb's action, the pluperfect subjunctive ('hubiera pasado') is used.

Common Mistakes

  • Using the indicative mood instead of the subjunctive.

    Él gasta dinero como si es millonario.
    Él gasta dinero como si fuera millonario.

    The phrase 'como si' always introduces a hypothetical, counterfactual situation, which requires the subjunctive mood. The indicative ('es') is used for facts, which is incorrect here.

  • Using the present subjunctive instead of the imperfect subjunctive.

    Ella me habla como si yo sea un niño.
    Ella me habla como si yo fuera un niño.

    Even when the main verb is in the present tense ('habla'), the rule for 'como si' specifically requires the imperfect subjunctive ('fuera'), not the present subjunctive ('sea'). The imperfect subjunctive signals the hypothetical nature of the comparison.

How It Connects

Tap a pattern to see what it builds on and what it leads to.

como si + Imperfect SubjunctiveLevel 4As if Construction

Learn This First

To use the 'como si' (as if) construction, you must first be able to conjugate verbs in the imperfect subjunctive, as this mood is grammatically required after the phrase to express hypothetical or contrary-to-fact situations.

Words in This Pattern

como si