Win8: How to Install .Net 3.5
In theory launching appwiz.cpl and clicking Add Windows Feature is the correct way to install .NET/3.5..
At this point Windows Update is to be queried and the content downloaded. This didnt work for me in build 8501. Hopefully this is better experience by final RTM build if not here is the work around.
Open an elevated command prompt and perform the following operations:
dism.exe /online /enable-feature /featurename:NetFx3 /source:c:\sxs