I have two class libraries. One is a C# Class Library (from Visual Studio 2015 -> New Project -> Installed -> Templates -> Visual C# -> Class Library). The other is C# Class Library (.NET Core) (from Visual Studio 2015 -> New Project -> Installed -> Templates -> Visual C# -> Class Library (.NET Core)).
I added a reference from my C# Class Library to my .NET Core Class Library, but it's not finding the namepsace when I try to do
You can't reference a pure .NET Core library from a classic .NET project as of today. You can, however, create a Portable Class Library (template "Class Library (Portable)", aka PCL) with targets ".NET Framework 4.x" and "ASP.NET Core 1.0". The resulting library can be referenced from Core and classic projects.