The dates are May 16, 2014 and June 27, 2014.
The Thor 2 release date has already been announced to be July 26, 2013.
Cosmic Book News will keep you posted!
The Avengers assembles May 4th, 2012 and is directed by Joss Whedon, starring Robert Downey Jr. as Iron Man, Chris Hemsworth as Thor, Chris Evans as Captain America, Samuel L. Jackson as Nick Fury, Mark Ruffalo as the Hulk, Scarlett Johansson as the Black Widow and Jeremy Renner as Hawkeye.
Head on over to the Cosmic Book News The Avengers Movie Hub for more news, images and trailers.