Only the specified folder and any subfolders that are beneath it will appear in the dialog box and be selectable. The FolderBrowserDialog.SelectedPath property, along with FolderBrowserDialog.RootFolder, determines what the selected folder will be when the dialog box is displayed, as long as FolderBrowserDialog.SelectedPath is an absolute path that is a subfolder of FolderBrowserDialog.RootFolder (or more accurately, points to a subfolder of the shell namespace represented by FolderBrowserDialog.RootFolder).