Yes, you can absolutely visit both Disneyland Park and Disney California Adventure Park in a single day using a Park Hopper ticket or a Magic Key pass. In 2026, the rules allow guests to "hop" between the two parks starting at 11:00 AM, provided they have scanned into their first reserved park earlier in the morning. Once the 11:00 AM window opens, you are free to walk back and forth between the two gates as many times as you like for the remainder of the day, subject to the parks' capacity limits. This is a popular strategy for visitors with limited time who want to experience "the best of both worlds," such as riding Star Wars: Rise of the Resistance in the morning and seeing the World of Color nighttime spectacular in California Adventure that same evening.