How do I edit the Visual Studio templates for new C# class/interface?

2022

Visual Studio 2022 is now a 64bit process so its location has changed to using Program Files instead.

%ProgramFiles%\Microsoft Visual Studio\<year>\<edition>\Common7\IDE\ItemTemplates\CSharp\Code\1033\Class.cs

2017 through 2019

Visual Studio 2017 changed the directory location to use release year instead of its internal version number, and is additionally dependent on your edition (Professional/Enterprise/etc.):

%ProgramFiles(x86)%\Microsoft Visual Studio <year>\<edition>\Common7\IDE\ItemTemplates\CSharp\Code\1033\Class.cs

2012 through 2015

Starting with VS 2012, the templates are not zipped, so you can edit each .cs template in each applicable folder directly.

%ProgramFiles(x86)%\Microsoft Visual Studio <version>\Common7\IDE\ItemTemplates\CSharp\Code\1033\Class.cs

2010 and older

Extract, edit and recompress the ZIP file. Paths are for the class template, but interface templates are in the same folder.

You may want to edit the VS template file in each to remove the fact that they don't automatically add references to the assemblies System, System.Data and/or System.Xml.

%ProgramFiles(x86)%\Microsoft Visual Studio <version>\Common7\IDE\ItemTemplates\CSharp\Code\1033\Class.zip

Notes

Express Editions

In Express Editions you will have to search in the subdirectory WDExpress inside the IDE folder, so e.g. for VS 2015 Express:

%ProgramFiles(x86)%\Microsoft Visual Studio 14.0\Common7\IDE\WDExpress\ItemTemplates\CSharp\Code\1033\Class\Class.cs

Other Languages

If you don't use the English version of Visual Studio, the folder 1033 may not exist, but a different number representing your language. For example it is 1031 in a German installation.

You're looking for the following directory:

C:\Program Files (x86)\Microsoft Visual Studio 9.0\Common7\IDE\ItemTemplates\CSharp

Each template is a ZIP file inside the 1033 (English) subfolder of one of the categories in this folder. You can edit the .cs file inside the ZIP file.

If you're on a 32bit system, remove the (x86). VS2005 is Microsoft Visual Studio 8, and VS2010 is Microsoft Visual Studio 10.0.

Note that these templates are not per-user. You can make per-user templates by copying those ZIP files to My Documents\Visual Studio 2008\Templates\ItemTemplates\Visual C#.