On the right side panel, go to Complimentary Admission, then blockout dates is toward the top of the page.
Not sure if you are looking for
Disneyland or Disney World dates, so here is everything:
Disneyland
May 2014: Sunday, May 4; Friday, May 16; Sunday, May 18; Friday, May 23
Disney California Adventure
May 2014: Sunday, May 4; Friday, May 16; Sunday, May 18; Friday, May 23
Magic Kingdom
May 2014: Thursday, May 1 thru Sunday May 4; Saturday, May 10; Saturday, May 17; Thursday, May 22 thru Saturday, May 31
Epcot
May 2014: none
Hollywood Studios
May 2014: Friday, May 23 thru Monday, May 26
Animal Kingdom
May 2014: Saturday, May 24 thru Tuesday, May 27