Document.DetectLanguage (Word)

Analyzes the specified text to determine the language that it is written in.

When applied to a Document object, the DetectLanguage method checks all available text in the document (headers, footers, text boxes, and so forth). If the specified text contains a partial sentence, the selection or range is extended to the end of the sentence. If the DetectLanguage method has already been applied to the specified text, the LanguageDetected property is set to True. To re-evaluate the language of the specified text, you must first set the LanguageDetected property to False.

With ActiveDocument 
 If .LanguageDetected = True Then 
 x = MsgBox("This document has already " _ 
 & "been checked. Do you want to check " _ 
 & "it again?", vbYesNo) 
 If x = vbYes Then 
 .LanguageDetected = False 
 .DetectLanguage 
 End If 
 Else 
 .DetectLanguage 
 End If 
 If .Range.LanguageID = wdEnglishUS Then 
 MsgBox "This is a U.S. English document." 
 Else 
 MsgBox "This is not a U.S. English document." 
 End If 
End With