Serene Highness

His/Her Serene Highness (abbreviation: HSH, second person address: Your Serene Highness) is a style used today by the reigning families of Liechtenstein, Monaco and Thailand. Until 1918, it was also associated with the princely titles of members of some German ruling and mediatised dynasties and with a few princely but non-ruling families. It was also the form of address used for cadet members of the dynasties of France, Italy, Russia and Ernestine Saxony, under their monarchies. Additionally, the treatment was granted for some, but not all, princely yet non-reigning families of Bohemia, Hungary, Italy, Poland, Romania and Russia by emperors or popes. In a handful of rare cases, it was employed by non-royal rulers in viceregal or even republican contexts.

The following titleholders or families are authorised by the Crown to use the style Serene Highness (French: Altesse Sérénissime, Dutch: Doorluchtige Hoogheid)

In the lodges of the Grand Orient of Belgium, the latter's Grandmaster is styled (fr) Sérénissime Grand Maître, (nl) Doorluchtige Grootmeester.

There is some evidence that in pre-Revolutionary France, unlike Germany, one entitled to be addressed as Serene Highness was considered to outrank someone who was addressed as merely Highness. Those members of the royal family who were not children or grandchildren of a king, i.e., the princes du sang, were entitled to be addressed as "Most Serene Highness" (Son Altesse Sérénissime, abbreviated S.A.S.). The simple style of "Highness" (altesse) was claimed by the princes étrangers and the princes légitimés. In fact, these formal styles were seldom employed in conversation, since the princes du sang used unique styles (e.g. Mademoiselle, Monsieur le Prince), while the ducal peers, led by the proud Duc de Saint-Simon, avoided conceding the altesse to the princes étrangers and bâtards royaux, prompting nobles of lesser rank to do likewise.

The current, legal usage of the style in the German-speaking countries is confined to the Princely Family of Liechtenstein, the entirety of which bears the treatment.

The German term is Durchlaucht, a translation of the Latin (su)perillustris. This is usually translated into English as Serene Highness, however, it would be more literal to translate it as superior to, above, beyond or greater than illustrious, as it is an augmentation of Erlaucht ("Illustrious Highness"), which was accorded to immediate counts (Reichsgrafen) of the Holy Roman Empire and by mediatised counts of the German Confederation and the German Empire. The 1911 edition of the Encyclopædia Britannica wryly observes that a perfectly logical English version might be "Your Transparency".

In 1375, Emperor Charles IV bestowed the nobiliary style Durchlauchtig upon the seven Prince-electors designated by the Golden Bull of 1356. As from 1664, Emperor Leopold I vested all Imperial Princes with the title, it became so common that the Electors like the Archdukes of Austria began to use the superlative address Durchlauchtigst. In the German Empire, the style of Serene Highness was usually held by princes of lower rank than those who were entitled to Highness (exceptions were the Wettin cadets of the Ernestine duchies), Grand Ducal Highness, Royal Highness, and Imperial Highness. Therefore, if a woman entitled to the treatment of Royal Highness married a man who was addressed only as Serene Highness, the woman usually retained her pre-marital style.

In 1905, Emperor Franz Joseph I of Austria granted the style of Durchlaucht to members of virtually every family which had held the title of prince in the former Holy Roman Empire, even if the family had never exercised sovereignty.