Guests will not be forced to use the MagicBand system, and people who do try it will decide how much information to share. An online options menu, for instance, will offer various controls: Do you want park employees to know your name? Do you want Disney to send you special offers when you get home? What about during your stay?

“I may walk in and feel good about giving information about myself and my wife, but maybe we don’t want to give much about the children,” Mr. Staggs said. Still, once using the MagicBand, even if selecting the most restrictive settings, Disney sensors will gather general information about how the visitor uses the park.

Rumors about MyMagic+ have been circulating on Disney fan blogs for months and offer a window into the likely debate over the service.

“Although I know this type of technology is making its way into every facet of life, it still makes me feel a bit creeped out,” wrote Jayne Townsley on StitchKingdom.com.

Pam Falcioni, another StitchKingdom user, had the opposite response. “I think it sounds awesome,” she wrote, adding, “As far as ‘Big Brother’ watching over us as we wander the parks, anyone worried about ‘real’ privacy wouldn’t be wandering around a theme park full of security cameras.”

The logistical challenges involved in pulling this off are extensive. Disney has 60,000 employees here and many must be retrained to use new technology. Already, Disney has installed free Wi-Fi at Disney World, a 40-square-mile area, so smartphone users can access the My Disney Experience app more readily. And all of the new procedures must be communicated to Super Bowl-size crowds daily.

What happens if your MagicBand is lost or stolen? Park employees will be trained to deactivate them or guests can use the My Disney Experience app, a Disney spokeswoman said. As a safety precaution, Disney will also require guests to enter a PIN when using the wristbands to make purchases of $50 or more. “The bands themselves will contain no personal identifiable information,” Mr. Staggs said.