The following works for me when the Winforms app is in the same folder as the calling cs program:
static void Main(string[] args) { Assembly MyCOB = Assembly.Load("WindowsFormsApplication1"); // DALL is name of my dll Type MyLoadClass = MyCOB.GetType("WindowsFormsApplication1.Form1"); // LoadClass is my class System.Windows.Forms.Form obj = (System.Windows.Forms.Form)Activator.CreateInstance(MyLoadClass); obj.ShowDialog(); } }