How do I find the fully qualified name of an assembly?

If you can load the assembly into a .NET application, you can do:

typeof(SomeTypeInTheAssembly).Assembly.FullName

If you cannot then you can use ildasm.exe and it will be in there somewhere:

ildasm.exe MyAssembly.dll /text

Use Assembly.GetExecutingAssembly() to get the current assembly, use Assembly.GetEntryAssembly() to get the assembly that started it all, or use Assembly.GetCallingAssembly() to get the assembly of the code that called your function (one up in the stack).

Once you have the right assembly, use the FullName property, as indicated in other answers.

If you load the assembly (DLL, EXE, etc.) in Reflector it will tell you the full strong name at the bottom.

Couple ways.

In code:

Assembly.FullName e.g.

typeof(Thingy).Assembly.FullName

or, if its an installed assembly, from the GAC using the steps in this post on msdn.

Being old-school and liking cmd better than powershell, I wrote myself this batch script to do it:

@REM fqn.bat <dll_path>
powershell -command "([system.reflection.assembly]::loadfile('%~f1')).FullName"

The %~f1 expands the first parameter to be an absolute path, so running:

fqn mydll.dll 

Will print the fully-qualified name you want.