Look in the help at the System.IO namespace and see which classes and which properties and methods are supported by the CF. The System.IO.FielStream.Seek method is supported, so this would suggest that it does. Random access applys to reading only though. If you want to insert or edit you must read in the whole file, make the changes and then write out the whole file, even in the full Framework. Apologies if you know this already but a lot of people seem not to.