What are the Spanish prepositional pronouns?

After a preposition Spanish uses: mí, ti, él, ella, usted, sí (reflexive), nosotros/nosotras, vosotros/vosotras, ellos, ellas, ustedes. They are identical to the subject pronouns except for the first two: mí (with a written accent, to tell it from the possessive mi) and ti (with no accent at all). So para mí, a ti, de él, sin nosotros, por ellos. The reflexive sí is used when the object is the same as the subject: lo quiere todo para sí (he wants it all for himself).

What are conmigo, contigo and consigo?

They are the fused forms of con + mí, con + ti and con + sí. Spanish never says 'con mí' or 'con ti'; it says conmigo (with me) and contigo (with you). The reflexive consigo (with himself/herself/themselves) is used when it refers back to the subject: se lo llevó consigo (he took it with him). All three are single words and only exist for con - every other preposition keeps the pronoun separate: sin ti, para mí, de ti.

Why is it entre tú y yo and not entre ti y mí?

A small group of prepositions takes the subject pronouns yo and tú instead of the prepositional mí and ti: entre (between), según (according to), excepto, menos, salvo (except), incluso, and hasta when it means 'even'. So it is entre tú y yo (between you and me), según tú (according to you), todos menos yo (everyone except me), incluso tú (even you). With these words, use yo/tú; everywhere else, use mí/ti.

Prepositional Pronouns

When a pronoun comes after a preposition - a, de, para, por, sin, con, en, sobre - Spanish reaches for a special set. The good news is that most of it is identical to the subject pronouns you already know; the surprises are all near the front. Para mí (for me), a ti (to you), con él (with him), sin nosotros (without us).

The set

After a preposition	Pronoun	Example
me	mí	para mí
you (informal)	ti	a ti
he / it	él	de él
she / it	ella	por ella
you (formal)	usted	para usted
himself / herself (refl)	sí	para sí
us	nosotros / nosotras	sin nosotros
you (pl, informal)	vosotros / vosotras	con vosotros
they	ellos / ellas	por ellos
you (pl, formal)	ustedes	para ustedes

Only the first two break from the subject pronouns. "Me" becomes mí - with a written accent, to keep it apart from the possessive mi (my). "You" becomes ti - with no accent at all (a very common spelling error is "tí", which does not exist). From él downward, they are just the subject pronouns.

Este regalo es para mí. (This present is for me.)
No voy sin ti. (I'm not going without you.)
Hablaron de nosotros. (They talked about us.)
Lo hago por ellos. (I do it for them.)

The reflexive sí

When the pronoun refers back to the subject, use sí (with an accent):

Lo quiere todo para sí. (He wants it all for himself.)
Piensa solo en sí misma. (She thinks only of herself.)

con is special: conmigo, contigo, consigo

The preposition con refuses to sit next to mí, ti, sí. Instead it fuses into a single word:

con + mí -> conmigo (with me)
con + ti -> contigo (with you)
con + sí -> consigo (with himself / herself / themselves, reflexive)
¿Vienes conmigo? (Are you coming with me?)
Quiero hablar contigo. (I want to talk to you.)
Se llevó el móvil consigo. (He took the mobile with him.)

There is never "con mí" or "con ti" - always conmigo, contigo. This fusion happens only with con; every other preposition keeps the pronoun separate: sin ti, para mí, de ti, hacia mí.

The exception list: entre, según, excepto, menos, incluso...

A short set of prepositions and preposition-like words rejects mí and ti and takes the subject pronouns yo and tú instead. Learn the list:

entre (between): entre tú y yo (between you and me)
según (according to): según tú (according to you)
excepto, menos, salvo (except): todos menos yo (everyone except me)
incluso (even): incluso tú (even you)
hasta (when it means "even"): hasta yo lo sé (even I know it)
Que quede entre tú y yo. (Let it stay between you and me.)
Según tú, no pasa nada. (According to you, nothing's wrong.)
Vinieron todos excepto yo. (Everyone came except me.)

With these words it is yo / tú, never "entre ti y mí" or "según ti". Everywhere else in the language, it is mí / ti.

Worked examples

No hay nada para ti aquí. (There's nothing for you here.) - a ti-type, prepositional.
Ven conmigo. (Come with me.) - the con- fusion.
Se rió de sí mismo. (He laughed at himself.) - reflexive sí.
Entre tú y yo, no me cae bien. (Between you and me, I don't like him.) - exception, subject pronoun.
Trajo a los niños consigo. (She brought the children with her.) - reflexive consigo.
Todos menos yo aprobaron. (Everyone except me passed.) - menos + yo.

Common mistakes English speakers make

Writing "tí" with an accent. Ti never carries an accent - there is no other ti to distinguish it from. Only mí gets the accent (versus the possessive mi).

Saying "con mí" or "con ti". These do not exist. It is conmigo and contigo, one word each.

Using mí / ti after entre and según. These take the subject pronoun: entre tú y yo, según tú - not "entre ti y mí".

Confusing mí (pronoun) with mi (possessive). Es para mí (it's for me, accented pronoun) versus es mi casa (it's my house, unaccented possessive). The accent marks the pronoun.

Most of the set is just the subject pronouns; only mí and ti change, only con fuses, and only that short exception list flips back to yo / tú. Master those three points and every preposition behaves.