There are several different Spanish equivalents for the English verb "to become," depending on several factors. (Note that in English, various verbs like "to get" and "to turn" are sometimes more idiomatic than the literal meaning "to become.")
Ponerse is followed by an adjective and indicates an involuntary physical or emotional change.
|Me puse enfermo en Madrid.||I got sick in Madrid.|
|Ana se pone roja cuando habla.||Ana turns red when she talks.|
Volverse is followed by an adjective and indicates a sudden, profound change.
|¡Se volvió loco!||He went crazy!|
|Julio se ha vuelto imposible.||Julio has become impossible.|
Hacerse and llegar a ser are followed by a noun or adjective and indicate a change brought about by effort.
|Me hice médico.||I became a doctor.|
|¿Es posible hacerse rico en los EEUU?||Is it possible to get rich in the US?|
|¿Llegarás a ser abogado?||Are you going to be a lawyer?|
|Llegó a ser muy popular.||He became very popular.|
Convertirse en and transformarse en are followed by a noun and usually indicate a change to a thing rather than a person.
|La condición se convirtió en una emergencia médica.||The condition turned into a medical emergency.|
|La leche puede tranformarse en queso.||Milk can be turned into cheese.|
There are also a number of Spanish verbs which express a specific change and tend to be somewhat more formal. When (se) is in parentheses, the verb may be used both intransitively and reflexively.
|adelgazar(se)||to get thin|
|cansarse||to get tired|
|emocionarse||to get excited|
|enfadarse||to get angry|
|enfermar||to get sick|
|enflaquecer(se)||to get thin|
|enfurecerse||to become furious|
|engordar||to get fat|
|enloquecer(se)||to go mad|
|enmudecerse||to go mute|
|enojarse||to get angry|
|enorgullecerse||to become haughty|
|enriquecerse||to get rich|
|enrojecer(se)||to turn red|
|ensordecer||to go deaf|
|envejecer(se)||to get old|
|palidecer||to turn pale|