In a previous post, I mentioned I used BZip2 for my compression - mainly because, it's simple, offers the best XML compression for a generic algorithm - IMHO, i.e., not one designed specifically for XML compression like XMill - which if anyone knows a C# or Java implementation of - please let me know. Anyway, you can get BZip2 (with a number of others) in the excellent SharpZipLib library. I really lament the lack of specific support for compression within the .NET framework, I mean the J# stuff has it in the java.util.zip namespace, would it really be so difficult to include this invaluable functionality within the framework proper? As it stands, you can encrypt but not compress data - there's no simple way to use compression from web services, you can't natively compress serialized objects - you can't really even open a compressed file without a third party plugin! XP now has compressed file support, why not the .NET framework!