There are two modules in this distribution. Date::Doomsday calculates doomsday for a particular year. Date::DayOfWeek uses the doomsday algorithm to calculate the day of the week for any given date. Doomsday is a cute little idea invented by Dr John Conway that makes it very easy to figure out the day of the week for any date. You can find out more about doomsday and related calculations at http://www.interlog.com/~r937/doomsday.html WWW: http://search.cpan.org/search?dist=Date-DayOfWeek