Its almost universally agreed that Sean Penn was at his best when he played Jeff Spiccoli in "Fast Times at Ridgemont High", but after that what do you think was his best performance as an actor?
Ironically, I thought his second best performance was another comedy, "Sweet and Lowdown". I thought he was very good in it, sometimes funny and sometimes sleazy and dishonest. What other movies was he good in?

That one where he played a surfer dude. Judge Reinhold was in that movie too, I think. Yeah, that was pretty fuckin' sweet.

Saving New Orleans

Yeah, that was the one, man. The name was on the tip of my tongue. My favorite part was when he ordered the pizza, FUCKING SWEET.

I thought he was incredible in Bad Boy (Not to be confused with the Martin Lawrence Movie.)

Whatabout the movie where he hits himself in the head with his shoe.....that was awesome.

I also liked him in "The Falcon and The Snowman" and "At Close Range". I just wanted to know what other movies you guys liked him in.

Heard he was pretty good in Dead Man Walking. Really liked Spicolli, but I was a little disappointed to hear that he stayed in character even when the cameras weren't rolling ... Great part, but did it really need THE METHOD. Maybe that is just movie legend.

I haven't seen Carlito's Way in a decade, but damnit, dick grayson just made me realize he's in that movie.

I'd say it's a tie between his roles in 21 Grams and Mystic River.

yep!

He was awesome in Team America.

Personally I thought he was best in the recent The Assassination of Richard Nixon.

I third his Carlitos Way performance.

Too many good ones.
Ones that have not been mentioned yet:

Colors
State of Grace
Casualties of War
The Thin Red Line

Mystic River, with Dead Man Walking a close second.

Dead Man Walking and he's extremely good in Hurlyburly.

At Close Range
Bad Boys