"I invited them to this event."

Translation: Zaprosiłam ich na to wydarzenie.

[ConeyBundock]

when would you use 'je' for them.

[Jellei]

If "them" consisted of women only. If there is at least one man among "them", grammatically that's "ich".

Oh, it wasn't accepted... that's a big oversight. It will be a starred answer as well now.

[ConeyBundock]

Thank you :-) Not only for this answer but also for the many helpful comments you contribute to this site.

[Arnoldpitt]

Hear, Hear. I also want to thank you all, particularly Jellleinfor your patient and helpful advice

[one_half_3544]

what about 'zdarzenie'?

[Jellei]

It doesn't fit the sentence, in my opinion. "zdarzenie" is just something that happened. So can be "wydarzenie", sometimes - although I'd go with 'zdarzenie'.. But "wydarzenie" can also be "an event" to which you can invite someone, something that is planned. "zdarzenie" doesn't have this meaning.

[Kami12087]

Do people use "wydarzenie" to mean a concert or a party? It sounds strange to me.

[Jellei]

Well, the Facebook tab "Events" is still called "Wydarzenia". I think people are usually simply more specific and say exactly what they mean and not 'event'.

On the other hand, I can easily imagine saying "W piątek robię imprezę, zaprosiłem cię na wydarzenie na Facebooku".

[Kami12087]

That example makes sense! I have been wondering if facebook is how "wydarzenie" became popularised in referring to social events.

But yes, when I think of telling someone in Polish that I'm inviting them to an event I'm hosting, I'd just be specific: "na imprezę", "na piknik". Just saying "zapraszam na wydarzenie" without providing any context sounds peculiar. (But in English it doesn't. One can say "I'm having an event on Friday, you should come", and people intuit that it's some sort of party.)