<p>I can use properties of an Excel Worksheet to tell if the worksheet is protected (Worksheet.Protection, Worksheet.ProtectContents etc).</p>

<p>How can I tell using VBA if the entire workbook has been protected?</p>

Worksheet.ProtectedContents is what you would need to use, on each Worksheet.
So I would set up a loop like this:
```
```
Public Function wbAllSheetsProtected(wbTarget As Workbook) As Boolean 

Dim ws As Worksheet 

wbAllSheetsProtected = True

For Each ws In wbTarget.Worksheets 
    If ws.ProtectContents = False Then 
        wbAllProtected = False
        Exit Function 
    End If 
Next ws 

End Function
```
```
The function will return True if every worksheet is protected, and False if there are any worksheets not protected.  I hope this is what you were looking for.