What "reflexive" actually means
A reflexive verb is one whose subject and object are the same person. Yo me lavo means "I wash myself" - the me is the reflexive pronoun marking that the action loops back onto the subject. The verb itself (lavar, to wash) is a perfectly ordinary -ar verb. The reflexive pronoun is the only thing that makes the construction reflexive.
Spanish leans on this construction far more heavily than English does. Many verbs that take a plain object in English are reflexive in Spanish: sentarse is "to sit" but literally "to seat oneself", irse is "to leave" but literally "to take oneself away", preocuparse is "to worry" but literally "to worry oneself". The English translation usually drops the "self" entirely; the Spanish keeps it.
The clue in the dictionary is the -se hanging off the infinitive. That -se is the reflexive pronoun in its citation form. When you conjugate the verb, you swap it for the pronoun that matches the subject.
The reflexive pronouns
There are six of them, one per grammatical person, and they map straight onto the subject pronouns.
| Subject | Reflexive pronoun |
|---|---|
| yo | me |
| tú | te |
| él / ella / usted | se |
| nosotros / nosotras | nos |
| vosotros / vosotras | os |
| ellos / ellas / ustedes | se |
In a simple statement, the pronoun goes immediately before the conjugated verb. Me llamo Juan (I'm called Juan). Se sienta (he sits down). Nos quedamos en casa (we're staying at home). Nothing slips in between the pronoun and the verb in a basic sentence.
In compound constructions where there's a conjugated verb plus an infinitive or gerund, the pronoun can either sit before the conjugated verb or attach to the end of the non-finite form. Voy a sentarme and Me voy a sentar are both correct and both mean "I'm going to sit down". More on that in a moment.
Walk-through: sentarse
Sentarse (to sit down) is an e>ie stem-changer that happens to be reflexive. The stem change follows the usual 1-2-3-6 rule (everywhere except nosotros and vosotros), and the pronoun shifts with the subject.
| Person | sentarse |
|---|---|
| yo | me siento |
| tú | te sientas |
| él / ella / usted | se sienta |
| nosotros / nosotras | nos sentamos |
| vosotros / vosotras | os sentáis |
| ellos / ellas | se sientan |
Sample sentence: Me siento al lado de la ventana (I sit next to the window). Note that the underlying verb sentar is regular -ar with stem change; nothing about the reflexive form changes how the verb conjugates. You're just gluing the right pronoun to the front.
Walk-through: irse
The most common reflexive in the top 1,000 and the most irregular. Ir is fully irregular on its own, and irse inherits all of that and adds the pronoun.
| Person | irse |
|---|---|
| yo | me voy |
| tú | te vas |
| él / ella / usted | se va |
| nosotros / nosotras | nos vamos |
| vosotros / vosotras | os vais |
| ellos / ellas | se van |
The meaning shift from ir to irse is worth flagging. Plain ir means "to go (somewhere)" and usually wants a destination: voy a casa (I'm going home), voy al supermercado (I'm going to the supermarket). Irse means "to leave" or "to be off", with the emphasis on departing rather than arriving: me voy ahora (I'm leaving now), se va sin decir nada (he's leaving without saying anything). Same verb, different angle on the action, signalled entirely by the pronoun.
The other three in this set
preocuparse (to worry) is a regular -ar reflexive. Full conjugation: me preocupo, te preocupas, se preocupa, nos preocupamos, os preocupáis, se preocupan. Example: Me preocupo por mi hermano (I worry about my brother).
quedarse (to stay) is also regular -ar reflexive. The yo form is me quedo; the él form is se queda. Example: Se queda en casa este fin de semana (he's staying at home this weekend).
alegrarse (to be glad, to cheer up) is the third regular -ar reflexive in this group. The yo form is me alegro; the él form is se alegra. Example: Nos alegramos de verte (we're glad to see you). The construction alegrarse de + infinitive/clause is standard for "to be glad about something".
All three follow the same template: take the regular -ar endings (-o, -as, -a, -amos, -áis, -an), bolt on the right pronoun, done.
A word on placement and attachment
When the reflexive verb sits in the infinitive inside a longer construction (ir a + infinitive, poder + infinitive, querer + infinitive, tener que + infinitive), you've got two equally correct options. Either put the pronoun before the conjugated verb, or attach it to the end of the infinitive.
Me quiero quedar en casa / Quiero quedarme en casa - both mean "I want to stay at home".
Both are grammatical, both are normal, both are taught in every textbook. Spaniards lean very slightly toward attachment to the infinitive; Latin Americans lean very slightly toward placement before the conjugated verb. As a learner, pick whichever you find easier to say and don't worry about it.
How to internalise reflexives
Stop treating reflexive verbs as a separate species. They're not. They're regular verbs (or stem-changers, or irregulars) with a pronoun riding along. If you can conjugate sentar, you can conjugate sentarse - it's the same conjugation plus me, te, se, nos, os, se depending on who's doing it.
The pronoun is a tag that travels with the verb. Put it directly in front of the conjugated form in simple sentences, and either before the conjugated verb or attached to the infinitive in compound ones. That's the whole mechanic.
The five verbs in this lesson - irse, preocuparse, quedarse, sentarse, alegrarse - cover the patterns you'll meet most often: one fully irregular base verb, one stem-changer, three regular -ar bases. Drill these to fluency and the rest of the reflexive system extends naturally as you pick up new lemmas.