And the tradition of dressing up actually came from the French:
"Read the rest of the article here to found out how the two traditions eventually intermingled and how trick-or-treating came into the mix.
There is an ongoing controversy as to whether we, as Christians, should participate in a day that the culture uses to promote the occult. Indeed the emphasis on the day has become similar to Christmas (in the commercial sense) with the seasonal costume stores set up like Christmas shops, and decorations on the lawns. Yet many Catholics have found a great way to bring it back to it Christian roots by emphasizing the feast of All Saints Day. By dressing as and learning about the saints, children get excited about the faith through the lives of these inspiring men and women. We can also take it as a tool of evangelization if we go throughout our neighborhoods trick-or-treating as the saints, being little lights for Christ.
We can go one step further by reminding ourselves, our children, and our friends that November is the month of All Souls. The souls are helpless without our prayers, and many are just waiting to be released from purgatory so they can enjoy eternal happiness in heaven. Pray for the souls you knew and those who have no one to pray for them. Have a holy day!
Update: As regards to Guy Fawkes Day (which was mentioned in the linked article), it is important to point out the following: the author of the article failed to point out that this day of "celebration" in England has been historically marked by acts of violence against Catholics. Raucous crowds often gathered to burn the pope in effigy. Though the anti-Catholic nature and rhetoric have been toned down, its still important to note its origins.