From the Disneyland website:
When is Disneyland Grad Nite 2012?
NEW DATES ADDED!!
May 10, 11, 14, 16, 17, 18, 21, 23, 24, 30 & 31
June 6, 7, 8, 12, 14, 19, 21 & 22 all have LIMITED availability
May 25 - SOLD OUT
June 1 - SOLD OUT
Disneyland will be EXTRA packed on June 14, due to...