If you want a very solid date/time library that is *very* easy to use for date calculations, I would recommend looking into the mx library. It has a DateTime sub-library that is wonderfully intuitive, and easy to work with. For example, a snip of mx.DateTime code: from mx import DateTime halloween = DateTime.Date(2002,10,31) weekBeforeHalloween = halloween - DateTime.oneWeek halloween_seconds = halloween.ticks() today_midnight = DateTime.today(0,0,0) # h,m,s I ran into a very similar problem last spring with daylight savings time while trying to generate a nice little calendar, and after I picked up the mx library it made life with dates 100% easier. hope that might help anyone struggling with date calcs in python, :paul

I stumbled upon a strange occurrence when I incrementally add days using the DateTime function.