Question: Is All Saints Day a Holy Day of Obligation?
In the United States and other countries, the bishops have received permission from the Vatican to abrogate (temporarily waive) the requirement for Catholics to attend Mass on certain Holy Days of Obligation, when those Holy Days fall on either Saturday or Monday. Because of this, some Catholics have become confused about whether certain Holy Days are, in fact, Holy Days of Obligation. All Saints Day (November 1) is one such Holy Day.
Answer: All Saints Day is a Holy Day of Obligation. However, when it falls on a Saturday or a Monday, the obligation to attend Mass is abrogated. For instance, All Saints Day fell on Saturday in 2008 and Monday in 2010; in both cases, Catholics in the United States were not required to attend Mass. (Catholics elsewhere may be; check with your priest or your diocese to determine whether the obligation remains in effect in your country.)
Of course, even in those years when we aren't required to attend, celebrating All Saints Day by attending Mass is a wonderful way to honor the saints, who constantly intercede with God for us.