Hi Janice!
Great question!
Currently, runDisney does not have any specific "walk-a-thons". BUT, all of the Disney races are walker friendly. You will see a large portion of walkers that walk the entire race. The only requirement is that you keep up a 16-minute/mile pace.
All runDisney races also have a wide representation of charity participants. There are dozens of charity groups that have runners and walkers in the events. RunDisney usually has one charity per race that is celebrated, but there are many more involved.
If you are looking for a charity group to join, you can find that information on the
runDisney website. If you click on the race weekend you are interested in, then click on the tab "REGISTRATION", you will find the charities listed there with information on joining.
I hope this answers your question! Please let me know if you have any others.