Yes, Disney can and does run out of park reservations, particularly at Disneyland Resort in California. In 2026, while Walt Disney World in Florida has largely removed reservation requirements for standard date-based tickets, Disneyland still requires them for all guests to manage capacity. During peak periods—such as the December holidays, spring break, or the opening day of a major new attraction—reservations for the Magic Kingdom or California Adventure can fill up weeks or even months in advance. For "Magic Key" holders (annual passholders), the "bucket" of available reservations is even smaller and often disappears much faster than for regular ticket holders. If you are planning a 2026 trip, it is critical to check the "Availability Calendar" before purchasing tickets to ensure your desired dates aren't already "greyed out."