Using class modules is separate mdb file

Is there a way to use a class module in an other database? For example, I have project1 with class module referedClass and project2 (with a reference to project1) I have a class referingClass and attempting the following:

Dim mreferedClass as referedClass

Sub setup()
set mreferedClass = new referedClass
‘ . . .
end sub

I then create an instance of referingClass but this results, when running setup, in a user-defined type not defined error at the Dim statement.

Thanks in advance . . .

John