Wedding etiquette says that the Mother of the groom is somewhat bound by the Mother of the bride's decision regarding the proper dress. The Mother of the bride decides how formal she wishes to go...floor length dress, tea length dress, a fancy suit etc. Then the Mother of the bride get to choose her color choice. As the Mother of the groom, you buy the same "type" (length) and style (dressy or not), suit or dress. You do not choose the same color the bride's mother has chosen. Any color other than her color is acceptable. A color that co-ordinates with the wedding colors is very nice but not a "have to". One hint - do not wear black. That is a very old fashioned way of saying you do not approve of the wedding.
