Private Sub Workbook_SheetActivate(ByVal Sh As Object)
Select Case Sh.Name
Case "Sheet1": 'do something
Case "Sheet2": 'do something else
End Select
End Sub
'This is workbook event code.
'To input this code, right click on the Excel icon on the worksheet
'(or next to the File menu if you maximise your workbooks),
'select View Code from the menu, and paste the code