Relative pronouns replace a noun or noun phrase when two sentences are joined together. Let's see the following examples:

- Abre este libro. Este libro está sobre la mesa.
  (Open this book. This book is on the table.)
- Abre este libro que está sobre la mesa.
  (Open this book which is on the table.)

- Este es el hombre. Este hombre ganó la medalla de oro en las olimpiadas.
  (This is the man. This man won the gold medal in the Olympics.)
- Este es el hombre que ganó la medalla de oro en las olimpiadas.
  (This is the man who won the gold medal in the Olympics.)

  Notice how in both examples the second phrase becomes a subordinate clause. Relative pronouns always refer back to an antecedent (a previously mentioned noun or noun phrase), which they agree with in number and gender. Unlike English, relative pronouns are always mentioned in Spanish.

Relative pronouns
Singular	Plural
que, el que(m), la que(f)	que, los que(m), las que(f)	which, whom
el cual(m), la cual(f)	los cuales(m), las cuales (f)	who, which
quien	quienes	who, which
cuyo(m), cuya(f)	cuyos(m), cuyas(f)	whose
cuanto(m), cuanta(f)	cuantos(m), cuantas(f)	what, how much
lo que (neuter)	used when there is no clear antecedent	what, which

 Prepositions are always placed in front of the relative pronoun, whichever form is used:
- El chico con quien salgo.
 (The guy I am going out with).
- Sé de lo que eres capaz.
  (I know what you are capable of).
- La chica de la que te hablé es mi amiga.
  (The girl I told you about is my friend.)

  "Que" is the most common relative pronoun in Spanish. As you can see below, it can follow a noun, pronoun, article or phrase.

- El estudiante que no estudia es mal estudiante.
  (The student who doesn’t study is a bad student.)
- Yo, que soy tu padre, te lo prohibo.
  (As your father, I forbid that.)
- Feliz es el hombre que alcanza sus metas.
 (Happy is the man who achieves his goals.)
- Todo lo que se ha dicho, que me parece muy bien, no puede cumplirse.
 (Everything that has been said, which I think is very good, cannot be fulfilled.)
- Todo lo que se aprende es útil.
 (Everything learned is useful.)
- Todos los que trabajan, triunfan.
 (All those who work succeed.)


 "Quien" always refers to a human antecendent and does not distinguish between masculine and feminine:
- La chica de quien te hablé es guapísima.
  (The girl I talked to you about is very pretty.)
- Los chicos con quienes hablamos eran de Alemania.
  (The guys we spoke with were from Germany.)

"Cuyo" is a relative pronoun, but it functions as an adjective, in the sense that it must agree in gender and number with the noun it accompanies.
- La casa cuyas puertas son marrones, pertenece a mis padres.
  (The house, whose doors are brown, belongs to my parents.)
- La chica, cuyo reloj encontré en la clase, es la novia de José.
  (The girl, whose watch I found in class, is José´s girlfriend.)

  "Cuanto" implies a vague, indeterminate antecedent, somewhat similar to "todo". It must agree in number and gender with the unexpressed noun:
- Dime cuanto sepas. (Tell me all you know).
- Dime todo lo que sepas. (Tell me all you know.)
- Entregamos flores a cuantas vinieron. (We gave flowers to all those who came.)
- Entregamos flores a todas las que vinieron. (We gave flowers to all those who    came.)

Notice that "cual" and "cuanto" appear in set phrases and expressions:
- En cuanto a mí, he decidido olvidar tu ofensas.
  As far as I am concerned, I have decided to forget your insults.
- José empezó a comer en cuanto llegó, y comia cual si estuviera muerto de   hambre.
  (José started to eat as soon as he arrived, and he ate as if he were starving.)
- El atleta corría como si estuviera en las olimpiadas.
  (The athlete was running as if he were in the Olympics.)

Click here to practice this an other aspect of Spanish grammar.