One way in which cabal can be made UAC aware (and therefore request for elevation privileges instead of just failing) would be to embed a manifest in the cabal.exe. This can be done by changing the default manifest (an XML file) that is embedded at link time by GHC. This is supported by GHC through compilation options. It could be used when building cabal for windows. The manifest itself is simple, it just needs one additional line to say it requires admin privileges. All details are here: http://msdn.microsoft.com/en-us/library/bb756929.aspx However, a problem with this approach is that cabal.exe as a whole would be seen as needing administrator privilege, regardless of whether the setting is global or user. If we want to request admin privileges only when actually needed (i.e., when writing in a protected folder). To address this, there are several options: - have two distinct executables for cabal, cabal-global and cabal-user with different manifest - use windows API for requesting elevation during the process (ugly) - use shellexecute command for running a process performing just the task that needs elevated privileges. Someone mentioned the "runas" command. But unlike su on linux, runas only changes the user, not the privileges attached to it. That is, on VISTA and 7, even admin users are seen as "standard user" unless they explicitly acknowledge they want to elevate a process with admin rights. So if you need admin rights while running as admin, you are only prompted for yes or no, while if you need admin rights as a non-admin user, you are also prompted for admin pass. This was done do address the legacy problem that everyone was using windows as admin in the first place. Also, the AppData folder is for application data, not for the application itself. I'm not sure how far one needs to go in terms of well-behaving for windows when it comes to multi-platform applications. I'd like to point out the "Application Compatibility Toolkit" which allows testing if an application is well behaved for vista and 7 and provides guidelines for that (it's a free download): http://www.microsoft.com/downloads/details.aspx?FamilyID=24da89e9-b581-47b0- b45e-492dd6da2971&DisplayLang=en you may also need to download the application verifier here: http://www.microsoft.com/downloads/details.aspx?FamilyID=c4a25ab9-649d-4a1b- b4a7-c9d8b095df18&DisplayLang=en You can use also on XP to test for vista and 7. I tried running it with cabal install somepackage and it points out a number of privilege errors. Note that if cabal was writing packages in AppData instead of "program files", then the problem would only surface when cabal install moves executable in the bin directory. It seems to me that the cygwin/mingw and, more generally, the GNU way of dealing with windows is to mainly ignore the directory structure of windows and install things in a separate directory chosen by the user (possibly in program files or elsewhere), requesting the user to manually change the path accordingly. That could be a solution to consider too. Hope this helps a bit, Regis