Is it a sin for Catholics to celebrate Halloween?

Which is it?

First of all, the word “Halloween” is a Scottish shortening of the phrase “Allhallow-even,” literally meaning “All Holy Evening” and dates to the 18th century. The English have a similar phrase, “All Hallows’ Eve,” with the same meaning. Both words denote the night before All Saints Day, November 1, and refer to the celebration of the holy men and women who are recognized in the Catholic Church as residing in Heaven.

Pope Gregory III established the feast during the 8th century after consecrating a chapel named in honor of All Saints in Saint Peter’s Basilica. The feast was then extended to the universal Church by Pope Gregory IV and declared a holy day of obligation for all Catholics.

Along with its celebration, All Saints Day was given a special vigil Mass the night before (October 31), which led to that date being regarded by Catholics as a “holy eve.”

Under this definition of Halloween, it is actually a holy night and is the opposite of evil.

Secondly, in the last 100 years, Halloween in the United States has become a night for trick or treating, when children go house-to-house in hopes of getting candy.

Again, there is nothing evil or sinful with children having fun, dressing up in costumes and receiving candy on the eve of a major feast in the Church.

What can be an occasion of sin is participating in any acts that are contrary to the Catholic Church.

The Catechism of the Catholic Church is clear about anything that seeks to glorify the demonic:

The key in any celebration of Halloween is to steer clear of anything that would bring undue attention to demons or Satan.

It's always best to consult a trusted spiritual advisor or priest about your observance of Halloween if you are unsure about how you approach the holiday.