Downcasting C# Generics...

This is one of the things that becomes stickier and more annoying due to my near constant jumping back and forth between Python (web apps and one-off data wrangling scripts) and C# (the current big project). But, it's bugged me for a while... It would be nice to have an easier way to handle the many situations of having on hand a List<DerivedClass> and needing to make use of that as a IList<BaseClass>. I realize that it's the sort of magic meta-programming often frowned upon in strongly-typed languages but I would be so happy if Generic Collections could provide even just IEnumerable<BaseType> for the base-chain and interfaces...