» Click here to see all Holidays Mother-In-Law Day   October 26, 2008   Click here to be reminded of this holiday Mother-In-Law Day Suggestions:  Gifts  Paper Greeting Cards  Free Ecards  'Mother-in-Law Day' is celebrated on the 4th Sunday in October. This tradition began January 23, 2002. It is similar to Mother's Day in that it is a day to celebrate motherhood. See Mother's Day. Mother-In-Law Day Suggestions View cards and gifts Join Now Free 3 month membership Learn More How does BigDates work? Get Holiday and Birthday Reminders