Once upon a time, a visit to a theme park like Disneyland was a formal occasion. People dressed up for it. In recent years a grassroots fan movement has become a full-blown frenzy as Disney fans come from all over to dress in their best for a weekend at the park. Some wear formal clothes inspired by their favorite Disney characters, while others dress in period outfits, fitting with the classic Hollywood theme that's part of Disney California Adventure Park. In the end, the point is just to look good. I spent the weekend in the park hanging out with my fellow Disney fans and got some pictures of some of my favorite outfits.I found the above couple dressed as Belle and Beast outside of the LEGO store in Downtown Disney, they were posing with their LEGO facsimiles that stand outside. Needless to say, it was the perfect place to catch them, as it shows just how great their outfits are. This is a perfect example of what many people wear on Dapper Day. It's clear that the outfits were inspired by Disney, at the same time, they wouldn't be out of place at another formal location.Another great way that people have fun with their dress at Disney is through the practice of Disneybounding. Disney Parks rules regarding adults in costume have gone back and forth over the years, but it's generally frowned upon. This has resulted in fans that have found a way to cosplay in secret, by wearing outfits that evoke particular characters, without outright dressing up as them. Here we have a Captain America and Black Widow inspired pair, along with a third who's gone with a more tradition Tiki Room inspired dress.Dapper Day began at 2011 and about 100 people are estimated to have gotten involved. Today tens of thousands show up for the events which take place twice a year, once in the fall and once in the spring at both Disneyland and Walt Disney World, with a fall event also at Disneyland Paris. In addition to the fans getting involved at the park, there's also an Expo that goes on inside one of the Disney hotels and musical performances available to folks who want to dance to period music.Check out the gallery below for more Dapper Day outfits, including looks inspired by Star Wars, Snow White, and even Hercules, not to mention lots of people just looking great.