There's an unforgettable moment on the road to any wedding: It's when you walk into an event at which people from every corner of your life are gathered together for the first time -- parents mingling with friends mingling with other relatives. Your older sister is getting to know your fiance's first cousin while your future father-in-law casually chats with your best friend from college. And though you may feel a moment of alarm as you consider the stories they could exchange about you, there is also something wonderful about this first glimpse of your family life as a married couple. For many couples, that moment occurs at their engagement party.

Engagement parties date to a time when marriage signified an allegiance between families as much as a romantic link between two people. In parts of England, for instance, a formal betrothal party known as a flouncing used to be held for a newly engaged couple. This event allowed the bride-to-be and her fiance to meet friends of both their families, and it also created what was essentially a legally binding contract. If either person broke the engagement thereafter, the wronged party could claim half of the other person's property.

Customs such as these slowly evolved into engagement-announcement parties, which were less binding but no less socially significant. By the early 1900s, newspapers were superseding parties as the preferred method of announcing a new engagement, prompting guidelines such as those Emily Post describes in the 1922 edition of her classic book on etiquette: "The prevailing custom in New York and other big cities is for the party to be given on the afternoon or evening of the day of announcement. The engagement in this case is never proclaimed to the guests as an assembled audience. The news is out, and everyone is supposed to have heard it."

With email, telephones, and far fewer social formalities to follow, the news these days is usually out before the bride-to-be has had time to realize she has said yes. But that doesn't mean your engagement should not be celebrated, or even formally announced, with a party. While traditionally the engagement party is hosted by the bride's parents, in these untraditional times it often turns out that friends of the bride and groom, or other relatives, want to host an engagement party as well. In that case, you may opt to have two or more parties: one for relatives and family friends, for instance, and another for your own friends. All the same, a good rule of thumb is to let the bride's parents have the opportunity to be the first to celebrate the engagement; even if a veritable stream of parties follows, theirs should be first.