Spanish modal verbs (verbos modales) express ability, permission, necessity, obligation, intention, or probability. Unlike auxiliaries, which only contain grammatical information without lexical meaning of their own, modals add lexical meaning in the form of the speaker's attitude toward the action, as well as grammatical information.

Unlike English modals, Spanish modals are conjugated for person and tense, but similarly to English modals, they are followed by the infinitive form of the verb.

While this makes them look like any other verb that can be followed by an infinitive (like intentar, preferir, gustar, oír, hacer, etc.), modals have characteristics that distinguish them from lexical verbs:

The main modal verbs in Spanish are:

When used in affirmative sentences, "poder" can express permission, ability, and possibility, similar to the English "can" and "may/might." For example:

When used in negative sentences, it shows prohibition or inability:

"Deber" is similar to the English "should" or "must" and expresses obligation or advice, depending on context. For example:

When negated, "deber" is semantically weaker and indicates that something is not recommended or not preferable.

"Soler" does not have a specific modal equivalent in English. It means to do something habitually or to tend to act a certain way. For example:

"Tener que" is similar to the English "have to" and expresses necessity or obligation, whether personal or external. For example:

When used negatively, this modal verb shows that the action is optional, not obligatory. For example:

When a sentence with modals verbs includes an object pronoun or reflexive pronoun, there are two options with regard to their placement. These pronouns can either come before the modal, or attach to the end of the infinitive. Here are some examples: