It’s unclear to me when the word ‘a’ comes before an infinitive in Spanish and when it shouldn’t. For instance suppose I want to say: “Trees help you to combat pollution” should it be “Los arboles te ayudan combatir polución” or should an ‘a’ come before combatir to make the sentence perfectly correct.

3 Answers 3


The confusion seems to revolve around the use of "a" before an infinitive in Spanish when "to" is used before an infinitive in English.

To decide whether "a" is required between certain verbs and an infinitive, some syntactic or, rather, semantic aids may be necessary.

As a general rule, the preposition "a" accompanies certain verbs to form verb phrases or to express an adverbial meaning, for example:

  • Ha comenzado a llover. (It has started to rain.) (Here "a llover" merely completes the verb phrase.)

  • Vamos a comer. (We are going to eat.) (Here "a comer" completes the verb phrase.)

  • Los árboles ayudan a combatir la polución. (Trees help (to) fight pollution.) (Here "a combatir" expresses the aspect in which trees can be of help.)

  • Te llevo a cenar. (I take you to eat out.) (Here "a cenar" expresses the purpose or the place I take you to.)

  • Está viniendo a estudiar. (He is coming to study.) (Here "a estudiar" expresses the purpose of his visit.)

The concepts of subject-matter, purpose, place, are said to be adverbial, because they modify the verb.

Instead, with verbs of volition, and verbs of liking and disliking, "a" is not used before the infinitive, and we can understand that the infinitive is, depending on the verb, the subject (only in the case of "gustar") or, so to speak, the object of the main verb (what is liked or disliked).

  • Me gusta comer (I like to eat, or as per Spanish word order, Eating appeals to me.) ("Comer" is the subject, that is, what appeals to me.)

  • Odio madrugar. (I hate to get up early.) ("Madrugar" is the object, that is, what I hate.)

  • Deseo leer. (I wish to read.) ("Leer" is the object, that is, what I wish.)

  • Quiero salir. (I want to get out.) ("Salir" is the object, that is, what I want.)

  • Adoro traducir. (I love to translate.) ("Traducir" is the object, that is, what I love.)

  • Prefiero enseñar. (I prefer to teach.) ("Enseñar" is the object, that is, what I prefer.)

  • Could you take a look at my ‘easy answer’ to my own my question? Thanks! Sep 8, 2022 at 3:21

Los árboles te ayudan (a) combatir (la) polución.

La frase correcta sería; // The correct phrase would be;

Los árboles te ayudan a combatir la polución.

Como reglas básicas sin entrar en pormenores, distinguir entre "a" y "ha";

  • "a" como preposición va delante de infinitivo. Ejem. a dormir, a comer, a combatir...

  • "ha" como auxiliar del verbo, va delante de un participio. Ejem. ha comido, ha llegado, ha rezado....

As basic rules without going into details, distinguish between "a" and "ha";

  • "a" as a preposition goes before the infinitive. Ejem. to sleep (a dormir), to eat (a comer), to fight (a combatir)...

  • "ha" as an auxiliary of the verb, goes before a participle. Ejem. she has eaten (Ella ha comido), she has arrived (Ella ha llegado), He has prayed (El ha rezado)....

Nota; Ayudar(se). 1. Cuando significa ‘ofrecer ayuda a alguien’, se ha generalizado su uso como transitivo en gran parte del dominio hispanohablante. Además del complemento directo de persona, suele llevar un complemento con a, si lo que sigue es un infinitivo, o con a o en si lo que sigue es un sustantivo:

Ejem. Alguien lo ayudó a incorporar la moto.


Debería estudiar la preposición "a" y cuando utilizarla con perífrasis verbales y algunos verbos como;

  • Ir a
  • Venir a
  • Salir a
  • Llevar a
  • Traer a
  • Contratar a

Con verbos de percepción;

  • Conocer a
  • Ver a

Verbos que denotan "selección";

  • Elegir a
  • Encontrar a
  • Escoger a

Note; ** Ayudar(se) - Help (himself)**. 1. When it means 'offer help to someone', its use as a transitive has been generalized in much of the Spanish-speaking domain. In addition to the direct person object, usually has a complement with a, if what follows is an infinitive, or with a or en if what follows is a noun:

Ejem. Someone helped him incorporate (to take in) the bike.

"Alguien lo ayudó a incorporar la moto"

" Los árboles ayudaron a combatir la polución"


You should study the preposition "a" and when to use it with phrasal verbs and some verbs like;

  • Come to (Venir a)
  • Go to (Ir a, Salir a)
  • Carry (Llevar a)
  • Will bring (Traer a)
  • Hire (Contratar a)

With verbs of perception;

  • Meet (Encontrar a)
  • See to (Ver a)

Verbs denoting "selection";

  • Choose to (Elegir a)
  • Will find (Encontrar a)
  • Pick a (Escoger a)
  • 1
    Then why is it: Me gusta comer and not Me gusta a comer? Aug 23, 2022 at 1:15
  • @Shinrin-Yoku does this Q&A spanish.stackexchange.com/questions/15699/… help?
    – mdewey
    Aug 23, 2022 at 9:44
  • El verbo "gustar", cuando es "gustar a", se refiere a alguien. Dicho de una persona: Resultar atractiva a otra. 5. intr. Desear a (alguien), querer a (alguien). The verb "gustar","like", when it is "gustar a", refers to someone. Said of a person: To be attractive to another. 5. To desire (someone), to love (someone).
    – Diego
    Aug 23, 2022 at 10:36
  • 1
    Al empezar a aprender a hablar español, solo aprendía los verbos. Quisiera que en ese momento alguien me hubiera aconsejado a aprenderlos más las proposiciones apropiadas, me habría ahorrado tener que volver a aprenderlos :-)
    – Traveller
    Aug 23, 2022 at 16:05
  • 2
    I love when somebody corrects my written English. About your comment: –... Habría querido en ese momento que alguien me aconsejase aprender mejor las preposiciones adecuadas...–
    – Danielillo
    Aug 23, 2022 at 17:06

Let me post an easy answer to my question. Put ‘a’ before an infinitive verb if in the English translation having ‘in order to’ before the verb does not change the meaning.

So “Como a vivir”, as “I eat inorder to live” is a perfectly correct translation. But “Me gusta comer” without ‘a’ since “I like in order to eat” is an incorrect translation.

  • 1
    The very first example in the answer Ha comenzado a llover shows that your ‘easy answer’ doesn't work, since ‘it has started in order to rain’ is nonsense. ‘Como a vivir’ is also wrong, como para vivir is the correct translation of ‘I eat in order to live’ IMHO
    – Traveller
    Sep 8, 2022 at 7:12
  • @Traveller It does not work always but does work mostly… Sep 8, 2022 at 15:13
  • Vamos a comer doesn’t (always) work either… If you’re using it as an infinitive of purpose, then your solution works but I suspect it’ll be wrong as often as it is right, because the grammar relating to ‘a’ is more complicated than a single usage
    – Traveller
    Sep 8, 2022 at 15:36

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