As in English, prepositions in Spanish need an object to be complete (for example, a sentence such as "I am going to" or "Voy a" doesn't make much sense). That object can be a noun or a pronoun (or sometimes a verb functioning as a noun).

Most of the pronouns used with prepositions in Spanish are the same as the subject pronouns, but they are different in the first- and second-person singular. Otherwise their use is fairly straightforward, as indicated in the following list:

mí — me

• Es un regalo para mí. It is a gift for me.
• Salieron sin mí. They left without me.

ti — you (singular familiar)

• Hablan de ti. They are talking about you.
• No valía nada mi vida antes de ti. My life before you was worthless.

usted — you (singular formal)

• Las flores son para usted. The flowers are for you.
• Ella no tolera fumar alrededor de usted. She doesn't put up with smoking around you.

él, ella — him, her

• Corrieron hacia él. They ran toward him.
• Fue escrito por ella. It was written by her.

nosotros, nosotras — us

• Vienen tras nosotros. They are coming after us.
• Andan al lado de nosotros. They are walking beside us.

vosotros, vosotras — you (plural familiar)

• No estoy contra vosotros. I am not against you.
• Salgo sin vosotros. I am leaving without you.

ellos, ellas — them

• El coche no es para ellos. The car isn't for them.
• Salgo con ellas. I am leaving with them.

There are two main exceptions to the above usages:

Conmigo and contigo: When used with con (usually translated as "with") the forms conmigo and contigo are used instead of con mí and con ti, respectively.

• Voy contigo. I'm going with you.
• ¿Vas conmigo? Are you going with me?

Use of yo and tú with certain prepositions: The following six prepositions are used with the subject pronouns yo and tú instead of mí and ti, respectively: entre (usually translated as "among" or "between"), excepto ("except"), incluso ("including" or "even"), menos ("except"), salvo ("except") and según ("according to"). Also, hasta is used with the subject pronouns when it is used with roughly the same meaning as incluso.

• Es la diferencia entre tú y yo. It's the difference between you and me.
• Muchas personas incluso/hasta yo creen en las hadas. Many people including me believe in fairies, or many people, even I, believe in fairies.
• Todos excepto/menos/salvo tú creen en las hadas. Everybody except you believes in fairies.
• Es la verdad según yo. It's the truth according to me.