Yes, you are absolutely allowed to exit Disneyland (or Disney California Adventure) and return later that same day. This is a common strategy for families who want to take a "midday break" to nap at their hotel or swim during the hottest part of the afternoon. To re-enter, you simply need to have your valid theme park ticket (either physical or on the Disneyland app) and, as of 2026, a Theme Park Reservation for that specific day. When you first enter in the morning, your photo is usually taken or linked to your ticket, which acts as your "identification" for re-entry, replacing the old system of ink handstamps. If you have a Park Hopper ticket, you can even exit one park and enter the other starting at 11:00 AM. It is important to keep in mind that re-entry is subject to the park's capacity; on extremely rare occasions, such as Christmas Day or New Year's Eve, a park may reach "Stage 4" capacity, meaning no one—even those who have already been inside—is allowed back in until the crowd thins out. However, for 99% of the year, popping out for lunch or a quick rest is a perfectly normal and encouraged part of the Disney experience.