Se passer has the meaning of to take place or to happen and takes être as does all pronominal verbs.

Passer can be used with a direct object (transitive) and takes avoir or with an indirect object (intransitive) and has to take être.

Hope this helps.

Alan

Just to build upon Jim's explanation:

-- Chris (not a native speaker).

Hello,

If I want to say "I passed by Bob's house today," I would say, "Je suis passe chez Bob." Is that correct? If it is, I don't understand how "chez Bob" is an indirect object. Just a bit confused here. Thanks for any help you can provide.