Yes, you can visit Disneyland Paris in a single day, but it requires a strategic approach. The resort consists of two parks: Disneyland Park and Walt Disney Studios Park, which are located just a few minutes' walk from each other. To see the highlights of both, you should purchase a "2-Park" ticket and arrive at least 45 minutes before "rope drop" (opening time). Focus on the major attractions early, such as Big Thunder Mountain and Star Wars Hyperspace Mountain in the main park, and Avengers Assemble: Flight Force or Ratatouille in the Studios. Utilizing the Disney Premier Access (the paid "FastPass" equivalent) is almost essential for a one-day blitz to skip long lines. It is also helpful to stay until the very end for the "Disney Illuminations" or the latest drone shows. While you won't experience every single minor attraction or meet every character, a well-planned 12-hour day is sufficient to cover the "must-do" rides and soak in the unique European atmosphere that distinguishes this resort from its American counterparts.