Prepositional pronouns (pronombres personales tónicos de preposición) are pronouns that follow a preposition (like a, de, con, para, sin, por). In Spanish, some pronouns have special forms when they appear after prepositions:

As you can see, most prepositional pronouns have the same form as the corresponding subject pronouns, except for first and second-person informal pronouns. Here are some examples:

If the subject of the sentence and complement of the preposition are the same person or thing (i.e. if a reflexive pronouns is needed) "usted," "ustedes," "él," "ella," "ellos," and "ellas" all change to "sí" after the preposition.

"Con" is a useful preposition in Spanish which causes some changes in the form of first and second-person prepositional pronouns as well as the reflexive form "sí." When used after "con," the first person prepositional pronoun attaches to the preposition and changes to "conmigo" while the second-person pronoun changes to "contigo." Additionally, if the object of "con" is the reflexive "sí," it changes to "consigo". But keep in mind that if the subject and object of "con" are not the same, the regular form of the prepositional pronoun (él, ella, etc.) must be used after "con." Check out the examples:

There are a few prepositions that require use of the same form as the subject pronoun in all cases. This means "yo" and "tú" are used instead of "mí" and "ti" after these prepositions. These include:

For example: