Reply #17: The best thing for me is to wait and see what the audience does.

[Alexander]

If they applaud between movements, I follow suit.

If it's one or two people who don't know any better, I don't clap.

I've attended countless classical concerts (and played some as well), and they're all different.

I know nobody is supposed to applaud until after the entire piece is over, but if everyone else is clapping due to a killer solo or a well-performed movement, I don't want to be the only one sitting on my hands.

While I normally loathe conformity, in this case it's best to just gauge the mood and follow the herd.