Determine .NET Version

Updated 2011-10-17

1) In the Registry Editor, locate the Registry Key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\

2) Compare settings to table on Microsoft site:

http://support.microsoft.com/kb/318785

Old Method

1) View properties version tab of mscorlib.dll in .NET framework folder.

Example:
C:\WINNT\Microsoft.NET\Framework\v1.1.4322\mscorlib.dll
File version: 1.1.4322.2032

2) Match up to Microsoft's list:

The released versions of the .NET Framework have the following version information.

Collapse this tableExpand this table

.NET Framework version	Revision	Version
3.5	Original release	3.5.21022.8
3.5	Service Pack 1	3.5.30729.1
3.0	Original release	3.0.4506.30
3.0	Service Pack 1	3.0.4506.648
3.0	Service Pack 2	3.0.4506.2152
2.0	Original release	2.0.50727.42
2.0	Service Pack 1	2.0.50727.1433
2.0	Service Pack 2	2.0.50727.3053
1.1	Original release	1.1.4322.573
1.1	Service Pack 1	1.1.4322.2032
1.1	Service Pack 1 (Windows Server 2003 32-bit version*)	1.1.4322.2300
1.0	Original release	1.0.3705.0
1.0	Service Pack 1	1.0.3705.209
1.0	Service Pack 2	1.0.3705.288
1.0	Service Pack 3	1.0.3705.6018

*The Microsoft .NET Framework 1.1 is included with the 32-bit version of Windows Server 2003.
(Microsoft Help and Support)

See Microsoft's web site below in References for latest list.

References
"How to determine which versions of the .NET Framework are installed and whether service packs have been applied." Microsoft Help and Support. 30 Jan. 2009 http://support.microsoft.com/kb/318785.

DLL Help Database
http://support.microsoft.com/dllhelp/?dlltype=file&l=55α=Mscorlib.dll&S=1&x=10&y=13