Paul,
Here at least your code needs error handling:
Sub ChangeStyle() Dim oDoc As Document, oSty As Style Set oDoc = ActiveDocument.AttachedTemplate.OpenAsDocument With oDoc For Each oSty In .Styles On Error GoTo Err_Handler oSty.LanguageID = wdEnglishUS Err_ReEntry: Next .Close SaveChanges:=wdSaveChanges End With ActiveDocument.UpdateStyles Exit Sub Err_Handler: Resume Err_ReEntry End Sub