Encyclopedia of American Holidays and National Days: Volume 1  
  Encyclopedia of American Holidays and National Days: Volume 2  
  Holidays - Kids InfoBits  

Crafts

  More of the Best Holiday Crafts  A collection of 65 holiday-based craft projects. In addition to Valentine’s Day, Earth Day, Easter, Halloween, Thanksgiving, Hanukkah, Kwanza, and Christmas, a number of new holidays have been added, including Flag Day, Memorial Day, 4th of July, President’s Day, and St. Patrick’s Day. There are creative decorations, favors, cards, and gifts designed to enhance holiday celebrations throughout the year.
 

Halloween

  Hooray for Halloween!  This site examines "the science of Halloween: bats, brains and cemeteries" (THE WHY FILES). Learn about the biology of bats, the study of the human brain, and the archaeology of burials through this humorous, Halloween-themed article.
 

Thanksgiving Day

  New Crafts for Thanksgiving  It features crafts such as gourd turkeys, pilgrim place cards, and a stick trivet.
 

World Holidays

  Holidays, Festivals, and Celebrations of the World Dictionary  Describes 2,500 holidays, festivals, commemorations, holy days, feasts and fasts, and other observances from all parts of the world. Entries cover popular, ethnic, religious, and historic events of international, national, regional, and local significance.
  World Holidays: A Rosen Guide for Children  A guide to celebrations and holidays around the world, including religious, civic, and cultural practices.