Running two projects at once in Visual Studio

Max has the best solution for when you always want to start both projects, but you can also right click a project and choose menu Debug → Start New Instance.

This is an option when you only occasionally need to start the second project or when you need to delay the start of the second project (maybe the server needs to get up and running before the client tries to connect, or something).

Go to Solution properties → Common Properties → Startup Project and select Multiple startup projects.