In short

Both the passive and the little word se let you talk about an action while pushing the doer into the background - often out of the sentence entirely. The first tool is the ser-passive, built like English “was written”: ser + participle, with the doer, if named at all, introduced by por. The second is the particle se, one word that does three different jobs - reflexive (ela veste-se), passive (vendem-se casas), and impersonal (vive-se bem) - and the trick is telling them apart, because the verb agreement changes with each. This lesson also settles two loose ends: which participle to use when a verb has two (foi entregue but tinha entregado), and how the verb agrees when the subject is a quantity like a maioria dos alunos.

The rule

The ser-passive with an agent

The passive turns the object of an active sentence into the subject: O júri escolheu o vencedor becomes O vencedor foi escolhido pelo júri (“the winner was chosen by the jury”). The recipe is fixed:

subject + ser (in any tense) + participle (agreeing) + por + agent

• Ser carries the tense: é escrito (present), foi escrito (PPS), vai ser escrito (future), tinha sido escrito (pluperfect).
• The participle agrees in gender and number with the subject, as in Lesson 24: a casa foi vendida, os livros foram vendidos.
• The doer is the agent, introduced by por - never de. And por contracts with the article (por + o -> pelo, por + a -> pela): foi assinado pelo diretor, foi fechada pela polícia.

You can drop the agent whenever it is unknown or unimportant - usually the point of a passive: O livro foi publicado em 2020.

The particle se and its three jobs

The same clitic se (placed by the rules of Lesson 30: enclisis by default, proclisis after negation and question words) covers three constructions.

1. Reflexive se - the subject acts on itself. Here se is a real pronoun, “himself / herself / themselves”, and the verb agrees with the subject: Ela levanta-se cedo. This is the se of Lesson 12.

2. Passive se (se apassivante) - the everyday way to say something is done without naming a doer. It works only with a transitive verb, and the direct object becomes the grammatical subject, so the verb agrees with it: Vende-se carro but Vendem-se carros. This is the se on shop signs (Aluga-se, Fala-se português).

3. Impersonal se - there is no subject at all. Use it with intransitive verbs or verbs that take a preposition, and the verb is always third-person singular: Aqui vive-se bem, Precisa-se de empregados. Because precisar needs de, empregados is not the subject, so the verb stays singular even though the noun is plural.

Double participles: foi entregue vs tinha entregado

Some verbs have two participles: a short irregular one and a long regular one. Choose by the auxiliary:

• With ser and estar (passive and state), use the short form: A encomenda foi entregue, A sala está limpa.
• With ter in a compound tense (Lesson 25), use the long form: O carteiro tinha entregado as cartas, A empregada tinha limpado a sala.

The exceptions are pagar, ganhar, gastar, which use their short form pago, ganho, gasto everywhere, including with ter (tinha pago).

Agreement with quantified subjects

When the subject is a quantity word plus a plural noun, agreement wavers:

• a maioria de + plural: standard is singular (with maioria), but plural (with the noun) is fully accepted: A maioria das casas foi vendida / foram vendidas.
• percentages + de + plural: the verb normally goes plural: Trinta por cento dos votos foram anulados.
• um dos que: the que points back to the plural noun, so standard grammar wants a plural verb: Este é um dos livros que se vendem mais.

Forms & patterns

Active turned into a ser-passive:

The agent contraction (por + article):

The three uses of se:

Double participles - choose by the auxiliary:

Examples

Common mistakes

• As casas foi vendidas. -> As casas foram vendidas. - in a ser-passive both ser and the participle agree with the plural subject: foram + vendidas.
• O relatório foi escrito por o diretor. -> … pelo diretor. - por contracts with the article, giving pelo / pela / pelos / pelas; never leave por o.
• O quadro foi pintado de um amigo. -> … por um amigo. - the agent of a ser-passive is introduced by por, not de.
• Vende-se casas. -> Vendem-se casas. - in the passive se the noun is the subject, so the verb agrees with it.
• Precisam-se de empregados. -> Precisa-se de empregados. - precisar de takes a preposition, so this is the impersonal se and the verb stays singular.
• Não fala-se inglês aqui. -> Não se fala inglês aqui. - negation forces proclisis, so se moves in front of the verb (Lesson 30).
• As cartas foram entregadas. -> As cartas foram entregues. - with ser / estar use the short entregue; the long entregado belongs with ter (tinha entregado), where European Portuguese also accepts tinha entregue.

Tips

• Use the ser-passive to keep the spotlight on the receiver of the action; add por + agent only when the doer matters: O bolo foi feito pela minha avó vs simply O bolo foi feito ontem.
• The passive se is what you read on signs - Vendem-se, Aluga-se, Fala-se português - and is often smoother than a full ser-passive. Agree the verb with the thing acted on.
• One test separates passive se from impersonal se: a direct object with no preposition means passive, so the verb agrees (Fazem-se chaves); a preposition between verb and noun (precisar de, falar de) means impersonal, so it stays singular (Precisa-se de chaves).
• Pick the participle by the auxiliary: ser / estar -> short (foi entregue, está limpo); ter -> long (tinha entregado, tinha limpado). Note pago, ganho, gasto are short everywhere (Lesson 25).
• With a maioria de, percentages and um dos que, let the verb agree with the plural noun if in doubt (um dos que sabem); with a maioria the singular is equally correct.
• In Brazil: the clitic se is normally placed before the verb, even to start a clause (Se vende, Se fala espanhol), and Brazilian writing often drops the passive-se agreement (Vende-se casas). European Portuguese keeps enclisis (Vende-se) and the plural agreement (Vendem-se casas).