Introduction
The phrase Impedir que is a common way to say that something prevents an action in Spanish. This article explains how to use it correctly, how it affects verb mood and tense, and shows lots of natural examples for beginners and intermediate learners. By the end you will understand the grammar rules, common verbs used with impedir que, and small cultural notes about formality and alternatives.
What does Impedir que mean?
The verb impedir means to prevent, stop, or keep from. When you want to say that one action prevents another action, you typically use Impedir que followed by a subordinate clause. The subordinate clause usually contains the verb that is prevented. For example:
Impedimos que ellos entren.
We prevented them from entering.
Structure and grammar basics
The basic structure is: main clause + impedir que + subordinate clause. The subject of the main clause is the agent doing the preventing. The subordinate clause contains the action that is prevented. Example pattern:
Subject + impedir + que + subordinate clause
Ella impide que yo hable.
She prevents me from speaking.
Use of the subjunctive
When the subordinate clause refers to an action that is not realized or is hypothetical because it is being prevented, Spanish uses the subjunctive mood. After Impedir que, use the present subjunctive for present or habitual prevention, and the imperfect subjunctive for past contexts when the main clause is in a past tense. Examples:
Present: El candidato impide que los niños participen.
Imperfect (past): La lluvia impidió que saliéramos al parque.
Notice that impidió is past indicative, and saliéramos is imperfect subjunctive.
Which subjunctive tense to use
Use present subjunctive when the preventing action is in the present, future, or habitual:
Mis padres impiden que yo salga tarde.
Use imperfect subjunctive when the main clause is in a simple past tense (preterite or imperfect) or when you are reporting a past prevention:
El profesor impidió que copiáramos en el examen.
In conditional or hypothetical past constructions, you may see pluperfect subjunctive when commenting about something that would have been prevented but did not happen:
Si no hubiera llovido, la tormenta habría impedido que voláramos.
Conjugation examples
Here are conjugation pairs showing the main verb impedir with subordinate verbs in the appropriate subjunctive forms.
Present: Nosotros impedimos que ella vaya al concierto.
Preterite: Nosotros impedimos que ella fuera al concierto. (less common — use impidió + fuera)
Preterite example: El guardia impidió que el hombre entrara.
Imperfect: La policía impedía que la gente saliera de la plaza.
Future/hypothetical: No creo que eso impida que ellos vengan.
Notes on verb agreement and subjects
The subject of the main clause and the subject of the subordinate clause can be the same or different. When they are the same, Spanish sometimes prefers a different construction to avoid awkwardness, like using a reflexive construction or infinitive. Compare:
Ella impide que ella hable. — a bit awkward.
Ella se impide hablar. — She prevents herself from speaking.
Or use an infinitive where grammatically allowed: Ella impide hablar a los estudiantes. — She prevents the students from speaking.
Common verbs and expressions often used with Impedir que
Impedir que frequently appears with verbs of movement, speech, access, or completion. Some common combinations:
Impedir que + entrar / salir / entrar / acercarse
Impedir que + hablar / decir / comunicar
Impedir que + terminar / lograr / completar
Impedir que + suceda / ocurra
Examples:
Los tornillos flojos impiden que la puerta cierre bien.
La niebla impidió que el avión aterrizara.
Alternative verbs with similar meaning
There are synonyms and near-synonyms to impedir you will hear in different regions or registers:
Evitar que — to avoid or prevent (often used when referring to deliberate prevention)
Imposibilitar que — to make impossible (stronger than impedir)
No dejar que — literal everyday alternative (less formal)
Examples:
No dejaron que los niños jugaran en el parque.
Evité que se publicara la información.
Formal vs informal usage and register
Impedir is neutral and fits both formal and informal contexts. For spoken, casual language, many native speakers prefer no dejar que as it sounds more natural and less formal. In written, academic, or legal language, impedir is very common. Example contrasts:
Formal: La ley impide que se produzcan emisiones peligrosas.
Informal: Mi madre no me deja salir esta noche.
Negative constructions and double negatives
Be careful with negatives. If you want to say that something does not prevent an action, put the negative on the main verb. The subordinate clause still takes the subjunctive if the meaning is hypothetical. Example:
La lluvia no impidió que fuéramos a la playa.
Here, it did not prevent us from going, so the action happened. The subordinate verb uses the imperfect subjunctive because the main verb is in the preterite.
Practical examples with translations
Below are natural sentences showing different tenses and contexts. Each includes a short translation to clarify meaning.
Presente: El mal tiempo impide que salgamos hoy.
The bad weather prevents us from going out today.
Pretérito: El accidente impidió que termináramos a tiempo.
The accident prevented us from finishing on time.
Imperfecto: La falta de fondos impedía que la escuela comprara libros nuevos.
The lack of funds was preventing the school from buying new books.
Futuro (with present subjunctive when expressing doubt): Es posible que eso impida que ellos vengan.
It is possible that that will prevent them from coming.
Conditional perfect context: Si hubiéramos tenido más cuidado, nada nos habría impedido que ganáramos.
If we had been more careful, nothing would have prevented us from winning.
Short cultural note on politeness
Using impedir can sometimes sound firm or formal. When asking for permission or explaining a rule politely, Spanish speakers often use softer verbs like no dejar, evitar, or indirect phrases such as es posible que or puede que. For example, in a polite request you might say:
Perdón, ¿puede decirme si esto impide que entre? — a bit direct.
Perdón, ¿esto no permitiría que entre? — softer alternative.
Common mistakes and how to avoid them
Mistake 1: Using the indicative in the subordinate clause after impedir que. Remember to use the subjunctive when the action is prevented or hypothetical.
Wrong: El ruido impide que ella llega.
Right: El ruido impide que ella llegue.
Mistake 2: Forgetting to switch subjunctive tense in past contexts. If the main clause is past, use imperfect subjunctive in the subordinate clause.
Wrong: La policía impidió que los manifestantes salen.
Right: La policía impidió que los manifestantes salieran.
Why the subjunctive matters
The subjunctive signals uncertainty, desire, or non-realized events. After impedir que, the prevented action is typically non-realized, which is why the subjunctive is required. Learning to pair common trigger verbs with the correct mood is one of the fastest ways to sound more natural in Spanish.
Quick reference summary
Structure: Subject + impedir + que + subordinate clause with subjunctive.
Present prevention: use present subjunctive.
Past prevention: use imperfect subjunctive after past main verbs.
Use alternatives like no dejar que or evitar que for softer or more colloquial expressions.
Conclusion
Impedir que is a practical and frequent way to express prevention in Spanish. Remember the key rule: follow with the subjunctive, and match the subjunctive tense to the time frame of the main clause. With practice and exposure to real sentences, you will quickly become comfortable using impedir que naturally in conversation and writing.
