Spring uses a simple logging abstraction in order to provide a layer of indirection between logging calls made by Spring and the specific logging library used in your application (log4net, EntLib logging, NLog). The library is available for .NET 1.0, 1.1, and 2.0 with both debug and strongly signed assemblies. Since this need is not specific to Spirng, the logging library was moved out of the Spring project and into a more general open source project called Common Infrastructure Libraries for .NET. The logging abstraction within the project is known as Common.Logging. Note that it is not the intention of this library to be a replacement for the many fine logging libraries that are out there. The API is incredibly minimal and will very likely stay that way. Please note that this library is intended only for use where the paramount requirement is portability and you will generally be better served by using a specific logging implementation so that you can leverage its advanced features and extended APIs to your advantage.