It's for anyone who wants to be "Irish" for a day. Here in Dallas, we had a parade on Greenville Avenue with 1,000 entries. There were floats, decorated cars, bands, dressed up pets, clowns, and just about anything else you could think of. It was a time for people to get drunk and stupid, and there were a lot of them. There was also an Irish Festival at a local park, and it was for owners of Irish Wolfhounds. Their owners didn't have to be Irish, but they all adopted Irish names for the day (e.g. O'Cardenas, McHernandez, etc.) All in good fun.