My understanding is that it dates to early celebrations of Guy Fawkes Day, when masked Protestants would show up at Catholic homes and insist on being served. It merged with Halloween when it arrived on these shores.

I just wonder if Wiccans don't get their collective noses in a knot; do you think modern witches ever decry that Halloween is getting too commercialized? hee hee
The term All Hallow's Eve is nice and quaint; nothing wrong with little mendicants begging for candy and sweets, and the dentists will be happy for the rest of the year. Wonder what they did in Germany when our good Papa was a boy.

Rich, I was told by a cultural anthropologist that it's actually older than that. Trick-or-treating comes from the same line as wassailing and wren-burying beggars around Christmas and St. Stephen's Day. The big difference is that while the other sorts of holiday begging rely on Christmas goodwill, the trick-or-treating relies on the assurance that people tend to be very generous when they have a good harvest.