Yes, as long as you have the XML documentation file for the assembly.
If the assembly is yours, you just need to make sure you generate the XML documentation file as part of your build process. Many third party code providers will also supply an XML documentation file for each of their assemblies, so you simply need to make sure these are stored alongside the relevant assemblies. .NET Reflector can also display the API documentation for most of the framework class libraries, but you don’t need to worry about finding the XML files for these.
Having verified that you have the relevant XML files, you now need to ensure that documentation display is enabled in .NET Reflector. Go to View > Options on the main menu bar, then click Disassembler in the list on the left. Now select Formatted from the Documentation drop-down. If you select XML Comments or None, no documentation will be displayed, although in the case of the former, this is probably a bug. Now click OK.
To view documentation for any type or member you need to make sure the Disassembler window is open. To do this just right-click on the type or member, then click Disassemble in the context menu. If the member has associated documentation, it will be displayed in a panel underneath the disassembler output or decompiled source code.
Note that we have had occasional reports of XML documentation support for the framework class libraries not working. If this applies to you the following information, and associated workaround, may prove useful.
If the XML documentation files for framework assemblies are stored only in culture specific directories below their associated assemblies, rather than alongside the assemblies, .NET Reflector may not be able to pick them up automatically.
mscorlib.dll is in C:WindowsMicrosoft.NETFrameworkv2.0.50727
mscorlib.xml is in C:WindowsMicrosoft.NETFrameworkv2.0.50727en
To fix this, copy the XML documentation files from C:WindowsMicrosoft.NETFrameworkv2.0.50727en into C:WindowsMicrosoft.NETFrameworkv2.0.50727. You should find that XML documentation for the framework assemblies will now be displayed in .NET Reflector, as expected.
We will aim to get this bug fixed in the next major release of .NET Reflector.