Hi Scott,
If you want to do this with a UserForm Try This:
Option Explicit
Private Sub Workbook_Open
If TextBox1 = "your pw" Then
"your code, what to do next"
Unload Me
Else
If TextBox1 <> "your pw" Then
Msg"Password Failed!" vbOkOnly + vbCritical
End If
End If
End Sub
James