Informative Caption tells me that this is “Halston Dinner Dance” on August 10, 1981 at Olympic Tower in New York City,” a building which is — in case you want to orient yourself in space and time — on Fifth between 51st and 52nd, and which has its own Wikipedia page. Apparently it was once very trendy, and also the NYT found it “oppressively banal.” (Halston didn’t live there; his place was decidedly non-banal.)
Why are people dining and dancing? Great question, friend! This is a party for Liza Minnelli and Robert DeNiro celebrating the re-edited version of their movie New York, New York, a fact I gleaned in part from this long contemporaneous piece in the NYT about Treat Williams. I did not even know about this movie, despite the fact that I love musicals, and its failure apparently “drove Scorsese into depression and drugs,”per its Wikipeda page. (He directed it. He wasn’t just a mega-fan who got really bummed out when it didn’t go well.) It had only come out in 1977, but I guess it did so badly that they cut it down and re-released it, and then later went back to it and added all that stuff back in and then added EVEN MORE STUFF back in, and then released it again. Maybe just let it go, Marty!
And, yes, all of those people were there. Come see!